Having visited and driven around southern Florida on at least four extended occasions, maybe six, I can assure you, there is no need to worry about a tag or tolls. I have never paid a toll in Florida, and have often seen the toll roads clogged with traffic, while on other roads, I was progressing unimpeded. One thing to watch though; there are some roads in the Miami area which have toll lanes, but not the whole road is tolled. Just stay out of those lanes. They are a bit like the HOV lanes.

Lifey.