Coupon Code Question

We are using MarketPress 2.8.1 for our website and would like the ability to have a coupon code be used on the quantity of item purchased, not just on the total price of the purchase.

Example: We have a $100 coupon code. When a person buys an item and uses the code, it takes $100 off, which is great. But if the person buys 2 of the same item in the same purchase, it still only takes $100 off, instead of $200 off ($100 for each item purchased).

Can this functionality be added to MarketPress? Thanks.