Florida sales tax is 6%, but groceries are not taxed at all. Neither are prescription medicines or most professional services. If you buy non-grocery items at a super market, those would be taxed, but not food.
Some counties have received legislative authority for higher rates of sales tax - I believe my home county is the highest with a 1% additional charge for a total of 7% - but those taxes would only apply to things taxed by the state...never groceries.
The tax that people encounter most at WDW would be a county resort tax. I'm not sure what it is, but the number 11.5% sticks in my head for some reason. Resort taxes would usually only apply to hotel rooms and some convention services though.