Scott is right, we are not supposed to answer blanket commission questions about what the standard is. We are able to talk about the average is, and about what we personally charge. I am a 6 percenter, anecdotally it seems to be the average here in Seattle.
There are several other options to a percentage based fee. Flat fee's for example. In my biased opinion, real estate is sales, and should pay accordingly. Why are sales people in almost all industries paid on a percentage commission, MOTIVATION. Sales is hard work, and money can be a great motivator.
Selling a house is a complex process and takes several people from title, lender, escrow, agent, broker, transaction coordinator. Getting them all to work together is not always an easy process. The best method known to get them all to work together is to pay them when the title has changed hands. This is the best way to insure they all do their job well. Flat Fee companies get paid first, removing them from this insurance.
I wish you luck and a great agent in Des Plaines.