Deductions & credits

If I amend my 2018 taxes to add sales tax of new car, what type of changes does that make to my 2018 return? is it a good thing or no? my filing status for 2018 was HOH and my return was 2,053.00 and taxable income was 26,430.00 after deductions and the sales tax on the paperwork 922.00 and 50 for county taxes. please can some guide me a bit?I really appreciate it. thanks in advance.