Deductions & credits

It's not sales tax.  You might be in the wrong area.  To get to the area to enter it: While inside the software and working on your return, type property taxes - auto in the Search at the top of the screen (you may see a magnifying glass there).  There will be a popup that says Jump to property taxes - auto.  Select that to get to the general area. 

If that doesn't work use vehicle registration fees in your search.