6% is the norm for single family, 10% for raw land, 4% for commercial property. All commissions are negotiable, but that must be done before signing the listing agreement.
Here's how the commission breakdown works: I am an agent and I work for ABC realty. I have an agreement with them that any property I sell, I get 60% of the commission and they get 40%. The 40% covers advertising, telephone, office space, etc. that they let me have.
I list your raw land and we agree to 10% commission. I sell it for you for $50,000. The check is made out to ABC realty for $5,000 and I get 60% of that. HOWEVER, if XYZ realty, John Doe sells the property, then the commission is split - $2500 to XYZ realty as the selling agency, and $2500 to ABC realty as the listing agency. I would get 60% of the $2500. John Doe gets whatever percentage he has worked out with his own agency - maybe they split it 50/50 or maybe he gets 100% of his commissions, and pays a monthly rental for office space, etc.