Hello!

PROBLEM:
- Tax calculates wrong when using a discount coupon (fixed amount, including tax) in the checkout.

SETTINGS:
- Zencart version 1.3.8a, fresh install with sample products, no mods installed
- My Store -> 'Display Prices with Tax' = true
- My Store -> 'Zone' = Florida
- Discount coupon fixed amount of $10.00, including tax
- 'ot_coupon' settings are: 'Include shipping' = false, 'Include tax' = true, 'recalculate tax' = none

CHECKOUT BUG: (I have added one product that costs $100.00 including tax) to make the calculation simple)

Sub-Total: $100.00
Store Pickup (Walk In): $0.00
Discount Coupon: 10 : -$10.65 (should be $10.00)
FL TAX 7.0%: $5.89
Total: $90.00

Where is the amount -$10.65 coming from? I have tried different combinations in the ot_coupons module, but with no luck. How is this supposed to work? Is there any documentation about how tax is calculated using different combinations of discounts etc?



Best Regards

Erik