One time, i scanned all of my items and had to wait for someone to check id because it included alcohol. After they unlocked the machine, I paid and left. Turned out that none of the scans registered after the first alcohol item, so i got a bunch of freebies. I'd normally give a shit, but this is how well they trained me and how well their system worked.
The process is perfectly designed to give you the results you got.
-Demming, or someone like him