I bought some granite for a countertop and was told that because it is considered a permanent installation in the home, there is no sales tax (Ohio). However, I bought a shower kit and there was sales tax. Why the discrepancy?
It appears that the guy who sold you the granite was mistaken. See this info; go to the top of the same page to see a list of FAQs answered here.
Note that this is very specific to Ohio.
On second look, this seems to apply:
Maybe a piece of granite is considered “building and construction materials” and you are the contractee. OTOH maybe a shower kit is not considered “building and construction materials” since it’s not raw materials and intended to be installed by the consumer. I don’t know.
Save your receipts, because the cost of home improvements can be deducted from the taxable profit when you sell your house. Or at least ask your tax preparer whether countertops and shower kits count.
That doesn’t say unless the contractee is in the State of Ohio. It says unless the contractee is the State of Ohio, i.e. part of the state government.
Oops, read too fast, making up words again :o Correct, so I was right the first time. 
IANATA but modifications that increase the value of your home raise the cost basis (which technically is not the thing as deducting it from taxable profit, but numerically ends up the same). If the shower kit replaced an equivalent shower that broke or wore out, or if the granite top replaced a broken one, then no increase in value and no increase in cost basis.
Depends on your state’s Sales and Use Tax Code.
In my state, any purchase for the home, regardless of its ultimate use, is subject to sales tax.
On the other hand, if I hire a contractor to purchase and install a counter-top, the contractor is not allowed to separately list the sales tax amount on a estimate or bill which accomplishes just about nothing because he is allowed to include that amount in the bottom line.
Detailed FAQs to OP’s state tax code linked in above post (although not the actual tax code, which even the FAQs say is very long and complex).
I would say that granite counter top is always an improvement to be capitalized unless you’re replacing existing granite, marble or something equally high end. But I tend to be conservative about these things.
One reason the distinction between “increase to basis” and “deduction from profit on sale” is important is that basis is used in many areas, such as depreciation if you use your home for a home office or convert it to rental property.