The clerk can preferentially show you higher margin products that might be what you're looking for, and while a grocery store wouldn't bother other retail (ex: electronics, cars) will.
“May I recommend the salmon today sir?” often means the chef got a good price on it and the restaurant will gross more.
Source: a friend of mine who bused tables for a few years. Not sure that’s statistically relevant in any way, but it’s an interesting anecdote.