Unlike a savings account that pays an interest rate, an IRA doesn't pay an interest rate. An IRA can be compared to an empty basket that must be filled with investment products such as stocks, bonds, ETFs, certificates of deposit, etc. A Roth IRA can increase in value over time by accumulating compound interest. When investments generate interest or dividends, that amount is added to the account balance.
Account holders can then earn interest on the additional interest and dividends, a process that can continue over and over again. The money in the account can continue to grow even without the owner making regular contributions. But the bottom line is that the amount of money you earn along the way will depend on your IRA's asset allocation. There is no such thing as an IRA interest rate.
In this way, Roth IRAs are the opposite of traditional tax-deferred or 401 (k) IRAs; with those accounts, you'll have to pay taxes when you withdraw the funds. The good thing about having an IRA, whether it's a traditional IRA or a Roth IRA, is that the money will grow tax-free while it's in your account. Instead, you'll be responsible for paying any IRA interest taxes when you receive traditional IRA distributions. You are not subject to the IRA interest tax on the interest your IRA accrues while they remain in your account.