A ROTH IRA can be invested into a wide variety of assets, such as stocks, bonds, CDs, and money markets. The yields on these investments will all vary depending on what you choose.
From how you phrased your question, I am thinking you want to invest in something like a CD or cash type of investment, is that correct?
You can start with WalletHub's tool here to get an idea on rates offered: https://wallethub.com/savings-account/
Not all banks listed may offer ROTH accounts though, so check on the bank's website first.
Publications like the Wall Street Journal publish daily savings rates for banks. Today's highest offer was from Think Mutual Bank: https://www.thinkbank.com/personal/bank/cd-ira.php
Is there a reason you are investing so conservatively in your ROTH IRA? If you are near retirement or in retirement it may make sense. But generally because of the tax advantages of an ROTH, you want to include more aggresive assets such as stocks and bonds.