If I was given the option of never having to carry metal coins with me any longer, I'd be glad to do that:
the shopping centres could offer to return the change instead of in metal coins in
BTC bitcoin as barcode on the cashier receipt.
you could use your Android phone to process that fairly quick then.
most cash printers already print barcodes and such. or use a code scheme involving webpages and PINs.
that would be a
huge petrol saver too, considering the reduced weight in street traffic thereby.
