From BMW Group PressClub USA:

Coming from a very strong performance in May 2009, MINI USA reported sales of 4,233 cars, a decrease of 8.2 percent.  Year over year, MINI showed a stable performance with 16,804 units, up 0.1 percent and continued to increase its share in a market that is still lagging other segments.

May 2010 May 2009 change year-to-date 2010 year-to-date 2009 change
4,233 4,610 -8.2% 16,804 16,780 0.1%

See MINI sales in the USA by month.