Just rented in TPA. Found out in advance that there were two, and only two, cashless tolls roadways - the Selmon and the Veterans, both of which were nowhere near where I wanted to be and easily avoided. Actually, the Selmon would have convenient but I just chose surface roads instead (using the "avoid tolls" mapping option).
I also crossed the Golden Gate Bridge each way last year in a rental car. After we got to the wine country, I called the toll-free number and prepaid that toll. However, when we did cross back southbound, there was a little hut after the toll booths that said "pay your toll here", so if you had neglected to do the prepay, you could have stopped and paid it on the spot.