Neither of the previous replies is correct.
The after-tax subaccount that was rolled over to Roth contained both after-tax contributions (box 5 amount) and pre-tax investment gains (box 2a amount), so the amount in box 2a must be included on Form 1040 line 5b.
For TurboTax to treat the taxable amount in box 2a as actually taxable you must answer Yes to either the question asking if you rolled over the money to a Roth 401(k) (or Roth 403(b)) or to the question asking if you rolled over the money to a Roth IRA. In this case the rollover was to a Roth 401(k) account.
