Sales Tax is primarily a method for revenue collection for greasy teenagers at fast food joints. It is also used by hired thugs and trained monkeys the local governments keep in cages until "tacks season," at which point they enter homes and steal money and anything they find with an original price tag. During this time, department stores hire hundreds of Hessians (drunken mercenaries, armed to the teeth) and tell them to shoot government monkeys on sight, fearing accidental intrusions. Sales tax is doubled on Tax Day, exactly six months after Tacks season, and the monkeys are given free reign for eight hours and locked up again. Iowa, Wisconsin, and China refuse to participate in the sales tacks ritual and are under heavy sanction from the Antarctic Union, whose primary export is government monkeys.
Sales tacks manuals are written in Latin and Greek, mainly to confuse the local population. In Greece, rumor has it that sales tacks law code is written in Chinese so it stays confusing. In most countries, tourists, politicians, and monkeys are exempt from sales tacks, which, according to official law, has a lot to do with the pointy end.
While Iron Man goes on a bicentennial government monkey hunt with the original Terminator, now Governor of California, sales tacks still exist because of their incredible rate of reproduction. Several small tribes of American Indians make their living off of sales tacks, souvenirs, and cigarettes, and on occasion gather outside the University of Illinois and Florida Seminoles games to protest sales tacks hunts.
Sales tacks relies mainly on the principle of Pyramid Taxation, which originated in Ancient Egypt, not to be confused with taxation without representation (propaganda used by the fountain fathers of the Ungrateful Stumps of Antarctica). Pyramid taxation was originally used to pay for ziggurats, but now exists so reigning monarchs can stick persons and corporations multiple times (see income tax, social security).
As sales tacks are mysterious beings, more information on them is greatly appreciated by rebellious philanthropic playboy superheroes-in-disguise, the Govenator, and any citizens that know Greek.