Can you trade a PS3 game for the same game but for XBOX 360?

They are businesses and of course since they will sell your your PS3 and Games for 3 times what you are paid they will take them in if they need those games and allow you to purchase the game and Xbox 360. You can not just exchange a used Black Ops PS3 for a Used Xbox 360 Black Ops you have to pay them maybe as high as $25-30