Apple has delivered an average return of 43.5 percent per year for the past ten years. Suppose you or your parents invested $100 per month during those ten years in Apple stock and placed it in a ROTH IRA.  You would have contributed $12,000.00 principal—but more importantly, have accumulated an investment gain of $190,211.00 with a total account value of $202,211.00.    When you reach retirement age (59.5 years), you will owe ZERO dollars in taxes on how much $202,211.00 has grown.