As someone else mentioned, consider getting an EZ-Pass. They're available at any oasis on the IN Toll Road and in many other states. For $10 you'll get the transponder which includes $8 in credits, and you'll pay about 40% less in tolls and not have to wait in line to use cash.
EZ-Pass is accepted in IL, IN, OH, PA, and several other states, and in several of them you can just roll by in an express lane without even slowing down. Your account is tied to a debit or credit card, and fees are automatically applied.
We find it to be a great convenience and a considerable saving.