TABLE 1: How SQL Server Rounds Datetime Values
Example	Rounded Example
01/01/98 23:59:59.999	1998-01-02 00:00:00.000
01/01/98 23:59:59.995, 01/01/98 23:59:59.996, 01/01/98 23:59:59.997, or 01/01/98 23:59:59.998	1998-01-01 23:59:59.997
01/01/98 23:59:59.992, 01/01/98 23:59:59.993, or 01/01/98 23:59:59.994	1998-01-01 23:59:59.993
01/01/98 23:59:59.990 or 01/01/98 23:59:59.991	1998-01-01 23:59:59.990