Asking for Stars during checkout

The Leads are telling people off today for not asking for Stars. Had a Lead pull me to the side today and tell me a secret shopper came through my line and notified them that I did not ask them to give me Stars. I was reminded that I HAVE to ask every single customer during every single transaction or I'll start getting in trouble. One of the 2 store Leads even came through front end to tell off our front end Leads because the numbers are low today.

I've seen and heard conflicting information on this topic. Are we actually allowed to ask for stars or will I actually get in trouble for not asking Every Single Customer ?