I drove down last August and used my EZ-Pass, so here's what I hit on the way down:
Starting from Hoboken, NJ and entering the NJ Turnpike at the Newark airport entrance 14 and exiting at NJTP exit 1 - $3.75
Delaware Bridge (DelDOT) $3.00
Maryland Fort McHenry Tunnel (MdTA) $2.00
Delaware Toll (Newark Plaza) $3.00
Total $11.75
You'd have to add a toll for either a tunnel or bridge to get through NYC, so figure $4.00 more for that plus a dollar or so more if you come over the George Washington Bridge onto NJTP/I-95 as you'll start from the exit 16 toll plaza.
If you don't have an EZ-Pass, you'll want to get one so you can go through the EZ-Pass express lanes and avoid the backups to pay the tolls manually. That will save you at least a half hour in waits at the tolls as the trucks really slow down the pay as you go lanes.
One other aside, I left at 11:30 am on a Thursday and was able to avoid the DC area traffic at PM rush, but got caught in the traffic south of DC on the way to Richmond that was quite heavy at just after 4 pm when I passed through there.