Tesco started that back in the late 90s and Sainsburys also did it 5+ years ago, then Tesco seems to have had another go at it recently.

edit: Safeway was first, in 1997

The Camden store illustrates the progress Safeway has made in other directions too. As part of its customer friendliness, Safeway was the first of the major food multiples to introduce self-scanning, the system it calls Shop & Go.

http://www.managementtoday.co.uk/uk-safeway-follows-leader/a...