Maybe, maybe not.  If the contributions are to a SIMPLE IRA, these are not deductible on your tax return.  Your employer has already excluded these from the taxable income reported in box 1 of your W-2.

If the contributions are to a Payroll Deduction IRA, simply a convenience provided by your employer to direct a portion of you paycheck to your own personal IRA and not an employer-provided retirement plan, these are treated as personal IRA contributions and are reportable on your tax return.  Whether they are deductible on not will depend on your AGI, your filing status and whether you (or your spouse, if married) is covered by a retirement plan at work.

If these are contributions you make through your employer to some other kind of retirement plan, these are not IRA contributions and are not reportable on your tax return.

Any amounts reported in box 12 of your W-2 are to be entered only on TurboTax's W-2 form, nowhere else in TurboTax.