Announced by IRS in October. Computed on bogleheads in September. Regular reading of bogleheads is rewarded; you would have saved four months of worry and doubt.
First computation, September 14, 2012:viewtopic.php?f=2&t=102688
Read down to neurosphere's calculation
$5568 rounded down to the nearest $500 = $5500.
Thus, the 2013 IRA contribution limits will be increased to $5500.
Ignore his doubt (which I conveniently left out). He was using the right rules, he just wasn't sure he was doing it correctly. He was (as tfb and I confirmed).
P.S. and your title is a little misleading: it's IRA, not Roth IRA.
For 2013, the maximum you can contribute to all of your traditional and Roth IRAs is the smaller of:
$5,500 ($6,500 if you’re age 50 or older), or
your taxable compensation for the year.