I was asked for my email address and straight away, a copy of the receipt was sent to my email address. This saves me the trouble of photocopying or scanning the receipt for safekeeping, particularly if the purchased items have warranty cover.
These receipts are printed on thermal paper which will fade. Hence, if you forget to make a copy in permanent ink, you may not be able to prove your purchase for the purpose of warranty claim or returning defective items.
It will be good news if all major retailers offer this type of service.