If I contributed to a Roth IRA via my employer's 401k plan do I answer yes or no to the question, 'Did you contribute to Roth IRA'?

No, do not enter this information twice. If you have a Roth-IRA through your employer, it will be reported with code AA in box 12 of your W-2.

You should only enter this information in the W-2 section of TurboTax.

The question in the IRA section is referring to IRAs that you set up yourself, for example, at your local bank. Contributions to this type of IRA are not reported on a W-2.

Also, the Roth account in your employer's 401(k) plan is not a Roth IRA.