How much off MSRP?

My 21 year old son just got his first post college job offer and it's actually a pretty sweet deal. He's got his heart set on a new IS as his first big boy purchase. I'm not saying I agree with him, but he's a grown ass man (at least in the eyes of the law). Are there any deals to be had? What percentage off MSRP are you guys getting? Last time I haggled w a dealer was in 2007 for my own IS (I miss that car) so I'm not up to speed on what's reasonable nowadays. Appreciate it!