I think it all depends on you. Obviously you are interested enough that you even ask, so whatever you do will be just great. I have had people give me money at residences where I never expected a dime, and businesses where they ship thousands of packages, and management doesn't do a thing the hourly get us a box of candy, or a gift certificate. And some just do nothing, because they say we get paid for what we do. And we do. It is the spirit of the season, and I think most will agree, its just nice to be remembered. Do what you can, and it will be appreciated, trust me it will be. Big or small. There is no set amount. I still favor on the side of gift certificates myself, because when I get to go to a special place, I remember why I am there, and sometimes money just goes, but thats just me. If hes a tool kind of guy, get him one from one of those places. Or even one from your own business if hes into what you carry is great too.