Possible bug in group discount and vat handling

Hi!

I am just setting up my first Zen Cart installation and experimenting with the various features. While testing the group pricing functions I might have came across a bug in 1.3.8a.
My setup is as follows:

Group discount
This module is installed
true
Sort Order
290
Include Shipping
false
Include Tax
false
Re-calculate Tax
Standard
Tax Class
Áfa

result:
40000Ft = Order total
33800Ft = Shipping
-20000Ft =Group Discount
7380Ft = Tax 20%
61180Ft = Total

with the tax calculation changed to None:

Rendelés összege:
40000Ft = Order total
33800Ft = Shipping
-20000Ft = Group Discount
7380Ft = Tax 20%:
68560Ft =Összesen

However this is what is should display:
40000Ft = Order total
33800Ft = Shipping
-20000Ft = Group Discount
10760Ft = Tax 20%:
64560Ft =Összesen

Both the total fields and the tax is wrong, since
1.) The system is set to give discount only on the product itself, not shipping. (the deduction is correct, it this case 50% from the product). While when calculating the taxes does Zen does deduct 50% from the shipping as well (what it shouldn't do as the discount is only valid for the product)
2.) in the second case the total is not correnct. the numbers just don't add up

Can you confirm that this is a bug (and not a feature :) and direct me to a solution. I tried to hack myself, but with no luck yet.

regards
Tamas

Perhaps this is the issue mentioned here:
http://www.zen-cart.com/forum/showpost.php?p=487733&postcount=10

DrByte:

Perhaps this is the issue mentioned here:
http://www.zen-cart.com/forum/showpost.php?p=487733&postcount=10

No, mine is not a division by zero thing (especially since I have items in cart).

The strange thing is that when I set the Re-calculate tax to Credit note than tha TAX is fine, but the order total isn't...

I tried editing the ot_group_prcing.php to see if there is something wrong there, I just couldn't find anything.

I had same problem. To resolve I set Re-calculate tax to Credit Note to get the tax calculation correct then changed the following line in ot_group_pricing.php:

if ($this->calculate_tax == "Standard") $order->info['total'] -= $tax;

to:

if ($this->calculate_tax == "Standard" || $this->calculate_tax == "Credit Note") $order->info['total'] -= $tax;

Problem solved.