> Order total is $100. - A $10 coupon code reduces the order to $90. - The order is completed and shipped. Later on the customer wants to return and get a refun

> Order total is $100. - A $10 coupon code reduces the order to $90. - The order is completed and shipped. Later on the customer wants to return and get a refund on one of the items. How much do you refund? Especially fun if the minimum order value for the coupon code was $99 and the product returned costs $5.