Target price adjusment

Something I ordered online went on sale the day after I ordered it. It shouldn't arrive until the end of this week as I ordered it Friday night, but I was just wondering if I can go in and get the price adjusted and on to a gift card before my package arrives? I know that you can do it if it went on sale within 7 days of purchasing, but I just want to know if I need the real receipt from the package. I have the email from target stating the order number, when I bought it, and the price I paid for it. Also I paid using a gift card