I remember training someone and at the end of their first cashier shift I asked them what they thought. They said it was pretty easy, but they needed to get better with the fruits and vegetables. I told them not to worry, you'll memorize the numbers with time.
They replied "No, I need to learn what they look like so I know what number to look for..."
I only worked at a grocery once as a summer job, but holy crap I sold a ton of 4011s. Nearly every customer bought them, or at least anyone who wanted to live. Basically the exceptions were the old women who instead bought cartons of Pall-Mall cigarettes.