In a situation where an order contains two different items, and the first item is returned and another of the second item is purchased, the original sales price of the second item is maintained:
A customer buys item X as well as item Y, which is on sale for 50% off.
After the sale on item Y has concluded, the customer returns item X and buys item Z as well as an additional item Y. Item Z is priced using the current pricing. But because item Y was in the original order, it maintains the original order pricing of 50% off.
