Hi Scott,
The feature which is referenced in our Change Log was inadvertently added as the client which requested the feature did not move forward with programming. I have removed this from the Change Log and added it to our Dev Roadmap because I think it would be a very useful enhancement.
What Tax Setting do you have configured in your Cart?
Depending on the jurisdiction, coupons may or may not reduce the sales tax which must be paid by the consumer. This is often determined by who sponsors the coupon. If the coupon is issued by the retailer, the product was never offered at the original price and the coupon represents a reduction in the amount paid and the tax. If the coupon is issued by the manufacturer, the original price is still paid but some of the price is covered by the manufacturer instead of the consumer and the full price remains taxable. This is the case with the coupon-eligible converter boxes in the U.S., which compensate in part for the forced conversion to digital TV. Mobile coupons have become very popular among US fast-food customers. The primary success factors for the SMS campaigns are discount size, how the discount value is framed (as a gift or percent off) and the timing of the campaign.
http://en.wikipedia.org/wiki/Coupon
As always there are a lot of rules and exceptions when it comes to tax and the rules and exceptions vary by country, state, province and sometimes city. The way the cart is programmed to apply tax on the original subtotal and not the discounted subtotal is correct in some countries and tax jurisdictions but in order to support all b2b and b2c stores we will need to add a new cart setting that allows the store admin to configure the cart to charge tax on the non-discounted subtotal or the discounted subtotal.
If would like to sponsor a portion of the development please submit your quote request here:
https://www.smith-consulting.com/Serv...
Please let me know if I can help with anything else.