Not a penny! Well, maybe lunch or a cocktail. All commissions are paid out by the listing side unless otherwise negotiated. If you are listing a rental with a professional, it's generally one months rent that gets split with another professional that procures a viable renter.
Buyer's, keep that in mind. It will not cost you a cent to hire a professional when purchasing a property. There are, however, times during the negotiation process, a buyer may be asked to split the commission costs with the seller. Speak with your professional and make the best deal for you.