https://dilbert.com/strip/1993-03-20
(I am not putting you down)
https://dilbert.com/strip/1998-03-17
My dad always disliked the strip you cite, because the change Dilbert expects is $5.25, but there's no way to provide $7.14 in a way that couldn't be trivially reduced to $2.14. If the goal is to make things easy for the cashier, he should obviously provide $2.14 and just keep the $5 he already has anyway.
(and I agreee - the first dilbert cartoon is super contrived)
The store actually had really great employees overall and I suspect this little factor played a big part in that. Part of the application process was a basic math test and it was funny to see how quickly some applicants recoiled when they found that out. It seemed to be a great filter.
About 10ish years ago I had an idea for a product that would essentially provide online training on this for cashiers. Back then I thought 'but everything is moving to cashless payments, plus more and more registers calculate change, no need for this". I wonder sometimes if this was The One That Got Away for me...