On a seasonally adjusted basis the May CPI-U for all items increased 0.1 percent over the month. The index increased 1.4 percent from May 2012, not seasonally adjusted. The small change was characteristic of all categories. Energy, which is often the most volatile category, saw an increase of only 0.4 percent, the first time this year the absolute change has been less than 1.7 percent. Medical care commodities declined 0.5 percent while all other categories increased or declined by less.
The official BLS news release is available here: www.bls.gov/news.release/pdf/cpi.pdf