On a monthly basis, retail sales were decreased 1.3% from April to May (seasonally adjusted), and sales were up 28.1 percent from May 2020.
From the Census Bureau report:
Advance estimates of U.S. retail and food services sales for May 2021, adjusted for seasonal variation and holiday and trading-day differences, but not for price changes, were $620.2 billion, a decrease of 1.3% from the previous month, but 28.1 percent above May 2020. … The March 2021 to April 2021 percent change was revised from virtually unchanged to up 0.9 percent.
This graph shows retail sales since 1992. This is monthly retail sales and food service, seasonally adjusted (total and ex-gasoline).
Retail sales ex-gasoline were down 1.5% in May.
The second graph shows the year-over-year change in retail sales and food service (ex-gasoline) since 1993.
Sales in May were below expectations, however sales in March and April were revised up.