I withdrew all my money from my ira account, but the investment was made from after tax money so will I have to pay 10% on the gross amount or interest earned?

Only the taxable amount of an IRA distribution is subject to an early-distribution penalty.  The taxable amount of the distribution from your traditional IRA will be determined on Part I of Form 8606 by taking into account the amount of your basis in nondeductible traditional IRA contributions, the amount of the distribution(s), and the year-end balance in your traditional IRAs.