Sales Invoices - Discounts - Chart of Accounts

When completing sales invoices, we offer discounts to our customers at the SKU level.  I would like to book those discounts to a separate chart of account code from the value of the product so we can capture and measure the amount of discounts we are giving to each customer.  Can you please add a feature that allows us to use a separate Chart of Account Code for the Discount at SKU level?