The Excel Ceiling.Math 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 Ceiling.Math function rounds a supplied number up to a supplied multiple of significance.
In general, positive values are rounded away from zero and negative numbers are rounded towards zero. However, the user can reverse the direction of the rounding for negative numbers.
Note: the Ceiling.Math function was first introduced in Excel 2013 and so is not available in earlier versions of Excel.
The syntax of the function is:
Where the arguments are as follows:
number    The number that is to be rounded up 
[significance]   
An optional argument that specifies the multiple of significance to round the supplied number to. If omitted, the [significance] argument takes on the default value 1 (i.e. round up to the nearest integer). (Note that the arithmetic sign of the [significance] argument is ignored). 
[mode]   
An optional numeric argument that reverses the direction of rounding for negative numbers only.

In column B of the following spreadsheet, the Excel Ceiling.Math function is used to round the positive and negative numbers 15.25 and 15.25, to different significance values.
Formulas:

Results:

The above examples show how:
For further details and examples of the Excel Ceiling.Math function, see the Microsoft Office website.
If you get an error from the Excel Ceiling.Math function, this is likely to be the #VALUE! error:
#VALUE!    Occurs if any of the supplied arguments are nonnumeric. 