I was going to ask, who came up with a dumb idea of using a link (i.e. URL) to access receipt data over the Internet, but fortunately it seems to not be the case - the QR code on the receipt posted by 'savant_d[0] reads:

  t=20170221T095900&s=30.00&fn=99990789659&i=501&fp=4189225230&n=1

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[0] - https://news.ycombinator.com/item?id=17601617