I only needed the previous 3 years and since I could only find 2 of them, I phoned up the IRS number and got them to send me their forms instead. Not sure if 1722 is what it's called now or not. I know when I got my interview letter, they had the old name for the form on there. The IRS told me its a new name but they should be able to figure out what you need. Just tell them previous records of your tax filings. Or do it over the internet like I did as well (got two sets of them)
I brought in my set for my interview and he didn't even look or ask about them, he just asked did you file your taxes since you've been here, I said yes, and he moved on. So they may not even want to see them, just depends...