I tip at restaurants where someone comes to my table to take an order and brings me my food. If I have to order it at a counter and then pick it up, I ignore the tip jar.
I also tip my barber and will throw a couple of bucks on the pillow in the morning when I have been at a hotel/motel. No way am I tipping my lazy ass mail carrier who folds and creases my mail.
If you have one, you should always tip your paper carrier unless they are a total screw up.