Are dividends from a 5+ year old established Roth IRA for a person over 70 1/2 tax free? I understand withdrawals of principal are tax free as they have already been taxed.
For a Roth IRA, everything withdrawn is tax free as long as you meet the age/time requirements.
You are correct that the contributions have been taxed; but the dividends, interest, and growth due to the price of the underlying securities are also tax free.
Also note - the key age is 59-1/2 for this to be true. 70-1/2 is when RMDs (required minimum distributions) take effect but there are no RMDs for Roth IRAs; you don't need to take any money out of a Roth IRA if you don't want to, and when you do take a distribution, it is (Federal) tax-free (subject, of course, to the 5-year and 59-1/2 years requirements.