"Sales price" or "purchase price" means the full amount received from the sale of property, including carrying charges when a dealer carries his own paper, delivery charges, manufacturers excise tax and any other additions to the selling price. No distinction is made between sales of new, used or trade-in equipment for tax purposes, all being taxed on the differences in the sales price and the amount allowed for a trade-in.
35 Miss. Code. R. 4-10-03-103