I have a product where the price is user supplied. It is essentially just a way for them to specify how much they are going to put on their credit card. We want to apply a 5% increase to the product total at checkout so if the user puts in $25 they are actually paying $26.25. Ideally, the checkout page would show a line item for the product and then a line item that says 5% with the additional $1.25. I have a promotion setup as a sale to increase the product price when the product SKU is 9900, however, the promotion never applies. Is there another way to apply the promotion to the order?