Rounding During Conversion To and From Money Types

The money and smallmoney types store four digits to the right of the decimal point, but rounds up to the nearest hundredth (.01) for display purposes. When data is converted to a money type, it is rounded up to four places.

Data converted from a money type follows the same rounding behavior if possible. If the new type is an exact numeric with less than three decimal places, the data is rounded to the scale of the new type. For example, when $4.50 is converted to an integer, it yields 5:
select convert(int, $4.50)

Data converted to money or smallmoney is assumed to be in full currency units, such as dollars, rather than in fractional units, such as cents. For example, the integer value of 5 is converted to the money equivalent of 5 dollars, not 5 cents, in the us_english language.