Applying a coupon code to cart subtotal less any product discounts
For signing up to our website's newsletter, we issued each customer a unique, one-time use 20% off coupon code. This code can be used in conjunction with any current promos on the site - some of our favorites to offer being "Buy One Get One for Half Price". All functions smoothly, except for one tiny issue ... I would like the 20% off code applied to the cart subtotal less discounts, instead of the cart subtotal alone. If product x is $16, and we have a BOGO 50% off, 2 total $24. But, the way I have the formula, the 20% off discount is $6.40 (.2 times cart subtotal), instead of $4.80. How can I tweak the formula, Jason?
