Buyer beware
 

Just gathered all my receipts together to make a list on my PC. Some of them were impossible to read due to cash registers ink run out. What would happen if you had to return to the shop with an almost blank print out. I bet the shop would give you a lot of grief. Just make sure when you get the receipt that its perfectly legible.

A lot of shops use thermal printers for till receipts which fade quickly if exposed to light

A bank statement or credit card statement should be proof enough assuming you didn't pay cash