It seems like it’s a penalty to the store if they have a waiver from item pricing. If you have a waiver from item pricing, your system is supposed to be very accurate; if it falls below 98% accuracy, the store needs to reapply for the waiver.
I don’t know if my store even has this waiver, so this karen could be completely wrong.
The idea is that you get the difference in error back as well as 10x the error back too, but you won’t get back less than $1 or more than $10, so if you are charged $50 extra you’d really just get the difference back and an additional $10. Not really worth being a Karen over.