The trick I’ve found over years of people-Ing as the person working is to always end with a statement that can either be turned back with ”you too!” without being awkward, or warrants something other than an autopilot response.

Thanks for stopping in, have a great night

Enjoy your meal and if you need anything just let me/us know

Don’t forget to tell your friends about us, and have a great day

Etc.

That way it’s totally fine for them to autopilot the pleasantries and they won’t feel cringey after.