Generally speaking, when you lump (or bundle) a taxable charge together with a charge for something that's not taxable, you will make the entire transaction taxable.
If I get my car fixed in North Carolina (and about half of the states), there's no tax on the labor, just the parts. But that's as long as the mechanic shows the parts and labor charges as separate items on the invoice. If he bills me $800 for the labor and $200 for the parts, then he would only charge me tax on the $200 of parts.
But if he just billed me $1000 for "parts and labor" with no breakdown, then I would have to pay tax on the entire amount.
There are variations on this rule, particularly for situations where the parts are insignificant in relation to the total invoice. And you'll see rules that set the amount of the taxes at 50% in some bundled situations. And here's another example of a combination of a sale of non-taxable services and taxable TPP.
But beware that this is a fundamental part of the way sales and use taxes work.
Sales Tax Guy