A colleague of mine just finished renting a car with AVIS and 3 weeks after he finished submitting his Expense Report, he got a bill form AVIS for $10.90 (the amount is not meaningful here). The detail around this was that it was for admiinstrative and toll charges. He paid all the tolls on the trip with cash, so this came as quite a surprise. Unbeknownst to him was that in the fine print there was a note saying that there is $4.50 a day administrative charge for tolls as there is a SUN PASS or EZPASS device already installed on the car.
Point is with AVIS, you should decline this in advance, letting them know that you will be paying all of the tolls yourself.