The Excel Round function rounds a supplied number up or down, to a specified number of decimal places.
The syntax of the function is:
Where the arguments are as follows:
number    The initial number. 
num_digits    The number of decimal places to round the supplied number to. Note that:

Column B of the following spreadsheet shows several examples of the Excel Round function:
Formulas:
 Results:

The above examples show how the Round function rounds up or down, to the specified number of decimal places.
If you require different rounding rules, check out our comparison of Excel Rounding Functions.
Further details and examples of the Excel Round Function are provided on the Microsoft Office website.
It is often a good idea to use the Round function when comparing two numbers in Excel, especially if the numbers are the result of multiple mathematical calculations. This is because multiple calculations may result in the introduction of rounding errors, which may cause small inaccuracies in the numbers stored in Excel.
For example, the decimal 5.1 may, due to rounding errors, be stored in cell A1 of your spreadsheet, as 5.10000000000001. When compared to the exact value 5.1, the value in cell A1 will not be equal to the exact value 5.1.
However, applying the Round function to the value in cell A1 removes the rounding error.
I.e. the expression:
or even the expression:
will evaluate to TRUE.