Starting in about 2000, dealers began jacking up invoice prices of the cars to include not only just destination charges, (which BTW have increased fourfold) but they now include various other charges like detailing, and believe it or not, an advertising surcharge. They pass the company ad costs on to the end user. At least they're up front about it.
I haven't bought a car since 2002, but when I did, I asked to see the invoice. I offered them $400 minus the holdback.
Take the invoice price, subtract the holdback, usually about $500 - $1500, and add $400. They'll usually go for it unless the car is so hot that they can get what they ask for. Most previous model year vehicles will fly out the door at $400 over invoice.
Give it a shot. All they can do is say no.