called PA Ezpass, added my rv, didn't know if I could but under 15k GVW I can. They asked if it had six wheels, yes.
Out of caution, got them to increase my standing account balance to 100 dollars.  Going through the Bay Bridge Tunnel and then later
out the PA Turnpike coming home, bet I eat up most of that.
What motivates me is not having to stop the rv, get out of the door, annoy everyone behind me, and then paying cash, can't get close enough 
to toll booth. Plus in some cases it saves a few dollars.
My EZPass has always worked well, except in Delaware, chronic problems there, had to write not once but twice to head of DEDOT to get their errors 
corrected. Which they did. 
The bridge toll is 14 bucks one way for a car.  I always ask the attendant, nicely, if a meal comes with that...

I'm guessing 30 bucks for the rv, have absolutely no idea.
Worst is PA Turnpike, you pay all that money for a bouncy miserable road that is constantly under construction.