Sorry missed this comment in prior post.......... To expand in what arbtrdr was saying, if there is tax to pay, it is suppose to be paid by the IRA that holds the investment and not personally by you which can cause other problems. Paying of the tax is technically in itself a taxable IRA distribution. I don't know why they have to make these things so darned complicated.
It's not that hard to determine if you have any taxable income from MLP's. They report their UBTI (Unrelated Business Taxable Income) on a line on the K-1 that they're going to send you for tax purposes. If the accumulated income from this line on all the MLP K-1's exceeds $1000, you have taxable income. Last year I received K-1's from 6 or 7 MLP's and none of them reported any UBTI. I have MLP's in our traditional as well as ROTH IRA's.
ETP has occasionally produced UBTI. MLPs need to be watched so that UBTI is under $1000. The rules with UBTI are VERY complicated. Also UBTI is cumulative for all MLPs and you count only positive UBTI and cannot offset with negative ones. Fine for a small amount but not for a very big investment.
Also be aware that technically you are liable for paying tax on the sale within an IRA - and yes I know this has never been enforced - so being aware of any changes in either tax laws or enforcement would be necessary as well. There are ways to avoid this but much too complicated for the average investor.