When specifying the number of decimals, IBM Cognos 8 uses the IEEE 754 default rounding mode known as half even. With half even rounding, numbers are rounded toward the nearest truncated value, unless both truncated values are equidistant, in which case the value ending in an even digit is chosen, as follows:
If the digit immediately after the precision to be shown is greater than 5, the number is rounded up.
If the digit immediately after the precision to be shown is less than 5, the number is rounded down.
If the digit immediately after the precision is a 5, the number is rounded down when the preceding digit is even and rounded up when the preceding digit is odd.
For example, the number 78.5 is rounded to 78, while the number 73.5 is rounded to 74.
In addition, if the maximum number of decimals is lower than the actual number of decimals in the number, the number is rounded to the maximum number of decimals.