Sales tax rates in Florida vary per county. The state sales tax is 6%, and each county adds a surtax.
Most of WDW is in Orange County, which adds 1/2% tax to the sate rate, making a grand total of 6.5% in Orange County.
South of Osceola Parkway is Osceola County. Osceola County's surtax is 1%, so the total tax in Osceola County is 7%. The only major portions of WDW in Osceola County are the All-Star resorts and the Wide World of Sports complex, so anything you buy in those places will be assessed the 7% tax rate.