I guess it is part tone or intent, I'll reply often "I'm good, how are you today (or doing, etc.) and get, "I'm ok (or I'm good, or "you know") and many times,

I guess it is part tone or intent, I'll reply often "I'm good, how are you today (or doing, etc.) and get, "I'm ok (or I'm good, or "you know") and many times, "thanks for asking" in a sincere tone. A sarcastic tone would throw off the cashier, or, if (my personal example) I am stressed or thinking of something else, of course my intent will be interpreted as "not caring," as, I probably don't. It doesn't take that Much willpower just to be nice to people, and many times, you will catch the "auto response must say hi how are you" verbists off guard in a good way.