Halls with complete packages - tipping?

I've been searching all old posts and I can't find anything about tipping at halls that come with a complete package (meaning that my photographer, DJ, limos, and videographer are included in the hall price). I paid an 18% service charge on the total price of the hall - so the tip is supposed to be included for everything. However, they said we could tip on top of that if we wanted - which I do want to do. But I have no idea how much! Everyone keeps saying a percentage - but I don't know how much the services were to begin with! Who should I tip and how much if they are already getting the 18%? Help! Thanks