DEAR ANNIE: Is saying “thank you” out of style now? If so, I need to change my ways. Polite people are seen as pushovers, I suppose. When leaving a grocery checkout, I usually thank the cashier, but shouldn’t they be thanking the customer? Rarely if ever does that happen! Do they not understand the customer is helping pay their wages so they can buy groceries? — Saying Thank You DEAR THANK YOU: Showing appreciation or gratitude is always a good idea. It makes you feel good, and it usually helps the person on the receiving end feel good, too. But expecting a cashier at the grocery store to say…