They do not count single sales in their album sales. I can't tell you the exact source, but I have heard an interview where Jon stated that their sales were full album sales only.

They had a huge hit with Who Says and hits always open doors for people to go out and pick up the back catalogue. How many people who grew up with Bon Jovi, turned to country, heard Who Says, and then thought, "Hey, I ought to upgrade Slippery to CD!"?