It's free from Fredericksburg to Daytona, and free on I4 from Daytona to Orlando.
Also, if you are coming from Central MA, there is a toll on the Mass pike from your exit through exit 7 (Ludlow). You would catch 291 to 91 South at Springfied, or 91 at exit 4 in West Springfield.
Also, of memory serves, if you have EZ pass (or fast pass if issued in MA) the tolls are slightly cheaper. I am not sure if what is quoted above is the discounted rate or not.
If you are driving from Central MA, and have a little more time, have you considered 84W, to 81S, to 17 south, to entering 95 in Fredericksburg? It's a couple of hours longer, but you miss the congestion through NY, NJ, MD and northern VA. This is the route we have done to go down south the past couple of times, and it is soooo less stressful.