You should safely set-aside 10% of your projected sales price for fixing the home, paying the agents and closing costs provided you need a fresh set of paint, carpets and a brandname realtor company like Century21 or similar.
If your home does not need any work and is spick-and-span, you probably need onlly 6% including 5% of overall realtor fees and 1% for closing costs.
If you plan to do the home selling with a 1% broker or Sale by owner, you probably can manage to set aside with 4% of the projected sales price.