From BMW Group PressClub USA:

MINI USA’s sales volume remained stable at 3,610 cars, versus the 3,605 units reported in the same month a year ago.  Year-to-date, MINI USA also reported sales of 8,728 automobiles, an increase of 2.5 percent.

March 2010 March 2009 change year-to-date 2010 year-to-date 2009 change
3,610 3,605 0.0% 8,728 8,513 2.5%

See MINI sales in the USA by month.