You can do it for $1. (or is it still 75 cents?) at one toll plaza.
Leaving the airport north exit, go left at the first light (Frontage Rd.) instead of immediately onto 528 the Bee Line (now the Beach Line). Little over a mile is next light (Conway), take two quick lefts to get on 528 there.
Watch carefully for toll signs and get over to the right and take what looks like an exit ramp to pay tolls in cash. Then you merge back on. You need a Florida transponder (Sunpass, E-Pass, not EZ-Pass) to use the main through lanes in that area.
Returning to airport via I-4 East (northeast) to 528 East, watch for the toll down the side ramp and then get off 528 at its exit 9 (Tradeport). Left and cross under. Get into middle lane. Required right onto McCoy (becomes Frontage). Next light is 436 (Semoran) and airport entrance.