it really depends on the person serving you.
This is key... I got served by a real grump the other night and would not play ball, straight down the line..
But today, I had my daughter asleep in the pram with me and the chick behind the counter was coo-ing at her, I could have cleared the store out after that... Was quite agreeable

Definitely a bit of personal engineering(there's another phrase for it) to be done...