>>3111899If you mean to imply that a person's earnings are taxed by income tax, and then by sales tax, and that these taxations constitute being taxed twice on the same earning... the presumption is false.
Sales tax is not levied against the purchaser, but against the seller's transaction. Naturally, the cost of that taxation is passed on to the seller, and is inherited by the products themselves.
https://en.wikipedia.org/wiki/Sales_tax 
