Good news to Receipt Hog users! You can upload your online receipts/invoices from shopping online! I just uploaded Amazon.com invoices and received coins for my transaction.
Simply take a picture of your laptop screen showing the online receipt. You do not have to print it out, but you can if you want to crush out personal information such as your name, address and credit card details. However you may still hide these information by being creative, and I recommend hiding these info for your protection!