I tend to blow that stuff off. It's part of their mindless training to be a cashier. The honey, sugar or sweetie thin doesn't happen so much here in the PNW but when it does my facial expression is usually enough to let them know I don't like it.
The cashier interaction is not usually where the real bs occurs, parking lots are my issue.

I saw this today. It might work.

“Responses to have a blessed day?” No change in facial expression, no acknowledgement of the comment, a controlled exit from the encounter.. As in, ‘shit,’ ‘there’s another one’....

I say "Thank you; you too". They're not being rude, merely saying something that to them is a meaningful, kind and pleasant thing to say. I appreciate their efforts even though I think their religious beliefs are claptrap and there's no point taking offence when a person's intention is the opposite.

On the other hand, when I worked in shops any customer who referred to a female member of staff as "sugar thighs" would have been told to leave the store immediately and not come back.

I sometimes reply, “I will if you will.”
Or I may get creative.
If I bought condoms I would gesture to them and say “Thanks, I will.”
Or, “Oh, thanks for reminding me, I need some vodka.”

Would you really be as disingenuous to Tiny Tim at the end of A Christmas Carol?

"Leaving is making it better already."

Why?