You should enter your Roth IRA contributions into TurboTax so that TurboTax can confirm that you have not made an excess contribution and so that TurboTax can track your contribution basis in case you ever take a nonqualified distribution.
(Just make sure that you don't confuse a designated Roth account in a qualified retirement plan like a 401(k) with a Roth IRA. Assuming that you are not self-employed, contributions to a designated Roth account in a qualified retirement plan are reported in box 12 of your W-2 and are to be entered only in box 12 of TurboTax's W-2 form, nowhere else in TurboTax.)
