Were they calculating it or had they "just" memorized the vast majority of common product combinations? I ask that, because I worked at 7-11 in Oklahoma for aw

Were they calculating it or had they "just" memorized the vast majority of common product combinations? I ask that, because I worked at 7-11 in Oklahoma for awhile, years ago. The Ok 7-11's are their own separate corporation. We didn't have scanners for anything except cigarettes, and it didn't take long before you knew total price, including tax, someone would have to pay for various combinations of standards prices (.99 + .99 + 1.05 + .59 or what have you). Mostly just a pedantic difference, but I thought I'd throw my experience into the mix. Still pretty crazy when you get someone that's been there awhile and knows basically all of them. I think my closest experience to this was when I was an order picker at a warehouse with no computers. We had guys on forklifts that seemed to know where every single item was in a warehouse with thousands of bays, and could tell you not just where something was, but what the number of the bay was. Pretty crazy.