George MANDL, Individual Trading as Mandls Bakery; Jenny Lee Bakery, Inc.; Potomac Bakery (Sub-Chapter S Corp.); Smiths Bakery, Inc.; Danity Pastry Shoppe, Inc.; Dalos Bakery, Inc.; Volz and Company, Inc., Trading as Rillings Bucks County Bakery; Weinrichs, Inc.; Key Bake, Inc.; Pennsylvania Bakers Association of Western Pennsylvania and Master Bakers Business Association of Philadelphia, Appellants, v. COMMONWEALTH of Pennsylvania; Department of Revenue of the Commonwealth of Pennsylvania; Department of Justice, Office of Attorney General of the Commonwealth of Pennsylvania, Appellees