I believe you have to be able to itemize deductions, before the sales tax deduction can come into play. So, you have to get to 24K (or more) before the sales tax deduction can be taken.
The Tax Cuts and Jobs Act modified the deduction for state and local income, sales and property taxes.
If you itemize deductions on Schedule A, your total deduction for state and local income, sales and property taxes is limited to a combined, total deduction of $10,000 ($5,000 if married filing separately).
Mike