Yes, you can ensure that no basis is rolled over to the 401(k) from the IRA by first rolling over to a Roth IRA in the same year an amount equal to your basis in nondeductible traditional IRA contributions. Since the amount of basis is apparently small, if the 401(k) ultimately declines to accept the rollover for some reason, making most of your Roth conversion taxable, the tax consequences of the Roth conversion will be minor. Just remember that all of your traditional IRAs are treated as a single account for the purpose of these calculations.
Your 401(k) plan will likely require you to provide them with a statement certifying that your rollover from the IRA contains no after-tax basis.
