While we can't know the exact details of your arrangement, it is almost always the case that if you buy, sell or cash out an asset held in an IRA, the cash stays in the IRA for you to invest again. As long as you don't withdraw the money, there are no taxes to you when the CD matures, and you have the choice of leaving it as cash or investing it in a new CD or something else, as long as you keep it inside the IRA.
