Canadians do you have this problem with taxes on Quantity discount addon?

I'm new here so be nice :-) using version 151 only the Quantity discount mod in place default template.

Having a problem with the quantity discount add-on.
Here is the situation:
order test:
35 items at 10.40 each total 364.00
The discount is set for 10% after 300.00 or 36.40 in this case so the subtotal is 327.60
In Canada we have 2 taxes one at 5% and 1 at 7%
so these taxes based on 327.60 are at 5% 16.38 and 7% 22.93 and that is correct
we also have to add tax to shipping but in this case no shipping no tax and that works
so we then total everything up

order total 364.00
discount (36.40)
subtotal 327.60
tax 1 - 16.38
tax 2 - 22.93
TOTAL - 362.54

And there is the problem:
When you add these together the total should be 366.91 Trouble is the total on the invoice shows 362.54 (4.37 difference) It appears that taxes are being calculated on the discounted amount of 36.40 pst 7% and gst 5% for a total of 4.37 and then that amount 4.37 is being deducted from the TOTAL only. If there is no discount, ie the price is under the 300.00 threshold it works fine. I'm going to try and attach some screen prints of the admin order sequence, and the Quantity discount Mod settings as well as a couple screen shots of the actual invoice created, not sure yet if that will work for me or not.

I've tried various combos in the discount mod such as include tax false and tax true, recalculate set to standard and to none and various combos of that. Tried moving the discount below subtotal and above. I get different totals but not the correct total of 366.91
I can move the discount above the subtotal, however it does not subtract from the discount from the subtotal no change the final total so I have left it below the subtotal to avoid customer confusion.

If the Quantity discount is not invoked (lower than 300.00) everything calculates fine, but as soon as the discount takes effect, the discount itself is correct, the taxes are correct, just the total is wrong because it takes the discounted amount and deducts tax to it in the total amount.

Any help? Any Canadians run into this?

Have you read my post on BC Taxes?

http://thecartblog.com/2013/04/15/my-zen-cart-discounts-with-different-taxes-for-shipping-vs-products/

Be sure the descriptions you provide for each taxation item are unique.

Ahh no I didn't, Thanks Scott. I'll go over it and make sure I have things set correctly and post back the test results.

So I read through the info on the link and just a couple of last questions before I backup and dive in.

You mention in the link http://thecartblog.com/2013/04/15/my...g-vs-products/
"in the discount module you use, skip over this tax when computing the updated amount of tax." what and where are the exact code lines/block in the OT_QUANTITY_DISCOUNT.php is the block of code/lines that need to be commented out or deleted?

And you display two blocks of code from 2 versions of Big Chooser, am I to inset them into the OT_QUANTITY-DISCOUNT.PHP and if so where?

Sorry for being a little thick it's late here and I've been on this since yesterday. Thanks for your help, much appreciated!

Please re-read the post. There are two blocks of code, and one is from Quantity Discounts. Make the changes described in that block. You only need to worry about the block from Quantity Discounts. You make the changes in includes/modules/order_total/ot_quantity_discount.php in the block of code that computes the taxes. Search for the switch statement on $this->calculate_tax; you will find it on line 359.

Thanks Software Guy!! It worked perfectly!