In buying a car the tag and title are a set price set forth by the state with a very small difference based on the person doing the notary work. Find out what that dealership charges. In most places tag and title are around 100 dollars. As for the tax, it will vary by state. Pa is .06. So to figure out tax for a car say 1000 dollars. Just use simple math. 1000 X 1.06. Or 1000 x .06 and add that number to 1000.