From my understanding, at least here in WI, sales tax is charged regardless on most of mylandscaping and lawn maintenance, with a few exceptions. Snow removal and ice control on the other hand is not taxed. Yes we do need to recover the sales tax paid on the salt material used, so figuring it in the estimate or final price has to be done, whether the customer can see it or not. I just think it makes things more difficult and makes costs of applying salt look higher when we have to figure in the so called hidden sales tax that we are trying to recoupe.