Stiles, tied for the first-round lead Thursday after a 66, birdied five of the first six holes in the final round on the Clearwater course. After a bogey on the par-3 ninth, he finished with nine straight pars.
Because the tournament was cut to two rounds, the victory will not count as an official win and Stiles won't receive exempt Nationwide Tour status through 2009.
The 34-year-old former Florida Southern player has four official Nationwide Tour victories, the last in the 2006 Rheem Classic. He played the PGA Tour last year.
New Zealand's David Smail shot a 66 to finish second at 9 under in the tournament sanctioned by the Nationwide and Australasian tours. American Rick Price (69) was another stroke back, and Australia's Adam Crawford (68) was 7 under.
New Zealand's Michael Campbell, the 2005 U.S. Open champion, followed his opening 70 with a 77 to finish at 3 over.