I need some suggestions, please...

Managers at my store are getting on my case because I don't 'interact' with customers at the checkout, when I cashier.

What I am looking for is a question I can ask, to satisfy them.

I already have 'how are you', but I was hoping for a question more relevant, something 'need to know' to help me serve the customer better. I already need to ask if they'd like help packing, so it doesn't count.

On the shopfloor, when a customer asks for help finding a product, I have 'Which kind of *product* are you looking for'; again, a 'need to know' question, which helps me. Something concrete, and related to checking out, because it's hard for me to ask irrelevant questions - even nice ones, like 'how are you?'