Yes, what everyone else said. 6% is the norm, looks like they gave you a break at 5%, and the buyer's agent would get half of that. (The buyer doesn't pay either agent's commission, it is all on the seller.)
As for the other closing costs, taxes, fees, etc, it can be a few thousand dollars as well. If you have never sold a home before, it really is amazing how much it adds up! I broke exactly even when I sold my home last year and was really hoping to have made a little more but those costs do add up.
As part of a negotiation, it happens somewhat frequently (or it did when I both bought and sold my house, same with my now-DH) that the buyer asks the seller to pay their closing costs too, so that is something to keep in mind when negotiating.
Good luck!