FLOOR Function (DAX)
Rounds a number down, toward zero, to the nearest multiple of significance.
The numeric value you want to round.
The multiple to which you want to round. The arguments number and significance must either both be positive, or both be negative.
A decimal number.
If either argument is nonnumeric, FLOOR returns #VALUE! error value.
If number and significance have different signs, FLOOR returns the #NUM! error value.
Regardless of the sign of the number, a value is rounded down when adjusted away from zero. If the number is an exact multiple of significance, no rounding occurs.
The following formula takes the values in the [Total Product Cost] column from the table, InternetSales.and rounds down to the nearest multiple of .1.
=FLOOR(InternetSales[Total Product Cost],.5)