Yes, you MUST include this on your tax return, not "should."
Under the law, all income is assumed to be taxable unless you prove otherwise. You need to actually file the return and sign it (or sign it electronically), which will certify for the IRS that all the facts and figures are correct, including your calculation about Roth contributions and withdrawals. Even though the IRS theoretically has the IRA records to figure it out on their own without your signature, they don't give you credit for any calculation you don't put in writing and sign your name to. If you leave it off your return, you WILL get a tax bill with interest and late fees.
