It depends. The question you should be asking is that service charge your being charged "all inclusive" meaning including gratuites, taxes etc.
It differs from caterer to caterer. I personally like to charge people all inclusive when I cater on the side. Although, in my experience, most people almost always kick in a little more to tip out the staff as it is customary. I know I personally throw some cash to the servers and bartenders that work a function that I have booked through another company.
I also only quote prices per person or per item instead of some round bottom line number.
Most folks want just a round figure that they will be charged, because they know what their budget is.
However, that doesn't always work for me because everyone is going to always try to negotiate your price down from that figure like they are buying a car, I know what my expenses will be upfront and what my time is worth, but it's harder to explain it in lump sum terms.
However, when you tell people the price you are going to charge by the person or item, I've found they sort of lose the incentive to negotiate, because the bottom line seems smaller by saying "I'm going to charge you $20 per person for the 200 coming to your wedding" instead of "I'll charge you $4000 for that." That way, when they start trying to nickel and dime you on the price, it makes it much easier for me to explain to the prospecitve client that they can't have certain things they want for less than the quoted price and can offer alternatives to fit with-in their budget. If they don't want to tip out the staff or seem really tight, then I'll build the gratuities into the price per person. Did I make it clear as mud?
