Say someone comes in and gets 10 units of Botox at $12/unit ($120) and the business charge is $8/per unit. The business should get $96 back before commission is paid out but if there is just a flat fee and it is not set per unit then they are only getting $8 back for 1 unit. and everyone gets a different amount of units so we can't just put a random number in the business service charge.