Incorrect Order Total With Coupon

[shinta]

I created a 10% coupon for my items. I had the Discount Coupon settings set to the following.

===================================

Discount Coupons

This module is installed
true

Sort Order
280

Include Shipping
false

Include Tax
false

Re-calculate Tax
Standard

Tax Class
Taxable Goods

================

When an item is checked out and this coupon is used, the total came out to be:

Item Price: $14.99
Discount Coupon: -$1.50 (correct)
Sales Tax: $1.11 (correct - at 8.25%)
-----------------------------------------------------
Total: $14.61 (incorrect!)

If you just grab a calculator and total up the three numbers, it should came out $14.60. Zen-cart is off by 1 cent.

How do I fix this?

I'm using Zen Cart 1.2.6.

[Kim]

How do I fix this?

I'm using Zen Cart 1.2.6.

Upgrading should cure the rounding error.

[baschwar]

I seem to be having trouble with this as well. I just recently upgraded to 1.3.0.2 and have read and tried a lot of the mods posted in the forums about the tax rounding issue.

My site is http://staging.mindmint.s402.sureserver.com/

My state sales tax is 8.6%. I am using a dollars off coupon based on order total. I have read that ZenCart will add the tax amount to each line item or quantity on a line item, then sum everything together, and do the rest of the calculations specified in the Order Total hierarchy. Is there no fix or way around this? My order totals are off more than a penny like some people mention.

Also -- when I go to delete the Sales Tax config and create a new one, it confirms that I would like to delete 9% sales tax, not 8.6%. What gives there???

Example:
2 x Freedom From Maternal Depression (2 Compact Discs) $88.00
Sub-Total:
$88.00

Standard US Shipping (Standard Rate 5-7 Business Days):
$8.50

Discount Coupon: SAVE5 :
-$5.00

8.6% WA Sales Tax:
$7.57

Total:
$99.07

This should really total $44 + $44 + $8.50 - $5.00 * 1.086 = $99.37
NOT $44 * 1.086 + $44 * 1.086 + $8.50 - $5.00 = $99.07

If this can't be easily fixed then what? I'm in a situation where configuring ZC has take me nearly a year and I would hate to scrap this and return money on this job just because ZC doesn't follow basic mathematical rules. What gives?

[DrByte]

Also -- when I go to delete the Sales Tax config and create a new one, it confirms that I would like to delete 9% sales tax, not 8.6%. What gives there???

The displayed value for this is determined by your setting for 'Tax Decimal Places' in Admin->Configuration->My Store.

[DrByte]

Example:
2 x Freedom From Maternal Depression (2 Compact Discs) $88.00
Sub-Total:
$88.00

Standard US Shipping (Standard Rate 5-7 Business Days):
$8.50

Discount Coupon: SAVE5 :
-$5.00

8.6% WA Sales Tax:
$7.57

Total:
$99.07

This should really total $44 + $44 + $8.50 - $5.00 * 1.086 = $99.37
NOT $44 * 1.086 + $44 * 1.086 + $8.50 - $5.00 = $99.07

Sounds like you've got Zen Cart set to not calculate tax on shipping or coupons.
Admin->Configuration->My Store
"Basis of Shipping Tax" should likely be the same as "Basis of Product Tax", and both should likely be set to "Shipping Address".

Then for Admin->Modules->Order Total->ot_coupon, you need to make sure you have it set to recalculate properly. ie:

Include Tax: true
Re-calculate Tax: Standard

You may also have your order-totals set in the wrong order (although what you show above for concept would be the right order). The defaults are:

COD Fee  	ot_cod_fee  	 ---
Discount Coupon	ot_coupon 	280 
Group Discount 	ot_group_pricing 	---
Gift Certificates ot_gv 	840 
Low Order Fee 	ot_loworderfee 	400 
Shipping 	ot_shipping 	200 
Sub-Total 	ot_subtotal 	100
Tax 	 	ot_tax  		300
Total 	 	ot_total 	999

[baschwar]

The displayed value for this is determined by your setting for 'Tax Decimal Places' in Admin->Configuration->My Store.

OK -- that helps a bit.

[baschwar]

Sounds like you've got Zen Cart set to not calculate tax on shipping or coupons.
Admin->Configuration->My Store
"Basis of Shipping Tax" should likely be the same as "Basis of Product Tax", and both should likely be set to "Shipping Address".

These were set as you prescribe.

Then for Admin->Modules->Order Total->ot_coupon, you need to make sure you have it set to recalculate properly. ie:

This was set properly.

You may also have your order-totals set in the wrong order (although what you show above for concept would be the right order). The defaults are:

COD Fee  	ot_cod_fee  	 ---
Discount Coupon	ot_coupon 	280 
Group Discount 	ot_group_pricing 	---
Gift Certificates ot_gv 	840 
Low Order Fee 	ot_loworderfee 	400 
Shipping 	ot_shipping 	200 
Sub-Total 	ot_subtotal 	100
Tax 	 	ot_tax  		300
Total 	 	ot_total 	999

These were all in the order you specify above.


I am still getting an incorrect tax amount as the method of calculating tax (as I understand it being used in ZC) is to tax each qty of a line item (as I showed in my example above). So, no matter what configuration changes I make my tax will be off.

DrByte- If you'd like access to the admin email me offline and I can get you in if you'd like to look around.

I'm at the end of my rope and ready to terminate this job, so any input you have would be greatly appreciated.

Thanks,

Brad

[DrByte]

A. Product Tax is calculated via this formula:
1. Select a product in the cart.
2. Determine its selling price
3. Determine the quantity of this item in the cart.
4. If one-time charges apply, add to the product's price
5. Determine the product's tax rate.
6. Calculate tax for the product.
7. Go to the next product and start again.

If the site is set to "include tax in displayed prices", then we simply loop through the products and calculate how much tax is included, so that it can be shown as a subtotal during checkout.

I think this is the same as what you had said you thought it should be in an earlier post.


B. So, next we look at shipping:

As to shipping rates, tax is calculated on shipping based on shipping-module settings and tax-basis settings. If you set a tax class on shipping, then shipping will be taxed according to that tax class's details... ie: depending on rate and zone, etc.

You've got the Tax Class in your shipping module set to "-None-", which means tax will not be calculated on shipping. Thus, the price you're seeing in the order-totals isn't including shipping taxes.


C. Finally, we look at coupons:
Coupons, like shipping rates, are also calculated based on the module settings. In the ot_coupon module, the default settings are:
- Sort Order=280
- Include Shipping = true
- Include Tax = false
- Recalculate Tax = standard
- Tax Class = none

Since you're desiring to have tax refunded where a coupon is used, you need to change the "Recalculate Tax" setting to "Credit Note" and change your Tax Class from '-none-' to the same tax class that your products and shipping are using.


That should do it.

[baschwar]

This definitely has solved my problem. Thanks for outlining the steps of the order total process.

Thank you, thank you, thank you!

Brad

[GlassHoppah]

Just want to add that Dr. Bytes configuration clarifications alleviated some, if not the majority of the issues listed in this thread for me: http://www.zen-cart.com/forum/showthread.php?t=40630.

BTW, Dr Byte--thank you--this post had some awesomely perfect timing.