Sometimes there are city taxes that do have nothing to do with the hotel and therefore need to be paid. I think the IC Berchtesgaden does charge those (in german it's called "Kurtaxe") and I would assume IC Rome does as I read that you have to pay a visitor tax now in Italy. Those are taxes that go straight to the city itself and the hotel has got no say in it whatsoever. I do remember there is a lengthly discussion on this in the IC Berchtesgaden master thread...