The Retirement contributions made through payroll are already counted and entered when the W-2 is entered.
So do not enter these again.
Go to Federal Taxes
Deductions and Credits
I'll chose what I work on
scroll down to Retirements and Investments and then to subheading Traditional and Roth IRA's.
Enter the max allowed and then TurboTax will tell you if you can do it or not, and it will also show the impact on the tax return.
