The Excel Mround function is one of fifteen rounding functions in Excel.
A full list, along with comparison tables, is provided on the Excel Rounding Functions page.The Excel Mround function rounds a supplied number up or down to the nearest multiple of a given number.
The syntax of the function is:
Where the arguments are as follows:
number    The number to be rounded. 
multiple    The multiple that the supplied number should be rounded to. Note: The multiple argument should have the same arithmetic sign (positive or negative) as the number argument. 
Column B of the following spreadsheet shows several examples of the Mround function:
Formulas:
 Results:

The above examples show how the Mround function rounds the supplied number to the nearest multiple of the supplied multiple argument. This may involve rounding up or down.
See the Microsoft Office website for further details and examples of the Excel Mround Function.
If you get an error from the Excel Mround function, this is likely to be one of the following:
#NUM!    Occurs if the multiple argument has a different arithmetic sign (positive or negative) to the number argument. 
#VALUE!    Occurs if any of the supplied arguments are nonnumeric. 