This is a fantastic solution!
Amazing - imagine the amount of time this will save! Yes yes, you might say only 1 second per transaction, but if you consider the average medium-sized supermarket serves in the region of 750 transactions per day, as most now open 7 days a week, that's nearly an hour and a half saved a week (750 seconds x 7 days), in one store alone. Extrapolate that to a year (750 seconds x 7 days x 52 weeks), and that one store has saved over 3 entire days - allowing them to either process more customers in that time, or employ staff for 7 less days a year (based on a shop opening 10 hours a day).
Take a massive chain such as Tesco, with over 1,500 stores in the UK processing as many or more transactions as above, and as an organisation they would be able to save over 113,750 man-hours. This equates to being able to shed the equivalent of 39 full-time staff across the company (based on working 8 hours a day). With average wages for checkout staff around £15k, that's half a million a year!
So, as you can see, that one second makes a lot of sense.
PS. I know my maths is probably still all wrong - you're lucky I worked it to this stage; at one point I had it so Tesco could close every store permanently and still be turning a record profit. Oh, and I'm not being totally serious with this being a great idea - although now I've done the maths, it does add up.