Search the forum ... Lots of discussion on the topic. But, assuming you're a member of Tread Lightly (good for 1% below invoice), you can generally land anywhere from 1-4% below invoice. Most seem to land at 1-2% below invoice.
Agree with the 1-2% price above, at least from what I've found. I started another thread today asking about the different car services.
As for used pricing, check out the Edmunds forums. There is a Smart Shopper section and within that a thread for Real World Trade values. Enter your TJs information and the regulars there will help you figure out a realistic price based on local auction prices. I did that for my last car and they were within $1k of the actual price I got.
I hope you meant BELOW, not above ... there's no reason to pay anything more than 1% BELOW invoice. A $60 membership to Tread Lightly will automatically get you 1%, again, BELOW INVOICE without any negotiation. Go down from there if you want/if the dlr will.