Toll-by-Plate does not work with rental cars.
The Toll Authority sends your toll charges to the rental car company, not you.

Daily Transponder Charges Toll Rates Maximum per Rental Contract
Alamo $3.95 Highest $19.95 + tolls
Avis $3.95 Highest $16.95 + tolls
Budget $3.95 Highest $16.95 + tolls
Dollar $15 per toll*$105
Enterprise $3.95 Highest $19.95 + tolls
Hertz $4.95 Highest $24.75 + tolls
National $3.95 Highest $19.95 + tolls
Thrifty $15 per toll*$105
Tolltraxx- 0 -Lowest tolls + .50 per toll

*If you don’t rent a transponder and still use a toll road

This is not the complete list and is subject to change without notice.