No. A Roth IRA contribution is not made through your employer. If you have a code AA or BB in Box 12 of your W2, that is not an IRA. Its a 401k or a 403b.
IRA contributions are not reflected on a W2 in Box 12. So, if you didn't personally open an IRA outside of employment, do not enter IRA contributions inside Turbo Tax.
Just select the appropriate dropdowns for Box 12 when entering your W2. You don't reenter any Box 12 selections anywhere else within Turbo Tax.