My name is on the student loan so how and where can I calculate any sales tax information?

What do you think your student loan has to do with sales tax?   What are you trying to do?    If you have a 1098E for paying student loan payments you enter the interest paid----that has nothing whatsoever to do with sales tax.

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WHERE DO I ENTER STUDENT LOAN INTEREST

https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-credits-deductions/enter-student-loan-interest-form-1098-e/L1QGfOUCp_US_en_US?uid=m6egbegu

Go to Federal>Deductions and Credits>Education>Student Loan Interest Paid (Form 1098E)

The student loan interest deduction can reduce your taxable income by up to $2500

There is a phaseout for the Student loan interest deduction, which means the amount you can deduct gets reduced when your modified adjusted gross income hits certain income levels and is even eliminated at certain income levels -  

You cannot deduct student loan interest if you can be claimed as a dependent or if you file as married filing separately