Really? We have always given 20, but they don't call every year even though the neighbour and both sons have been pompiers. Liable to be even less frequent now since Boss came to live here. Although he wouldn't deter them from their regular visits to cart Fran off to hospital after yet another stroke.
The postman is at work, so goes against the grain somewhat, but I did use to give him something years ago when he pulled a cord to a bell to let me know there was something. I discontinued the practice when I ditched the bell arrangement, haven't noticed any resentment or diminution of the service.