Excel Round Function

The Excel ROUND function returns a number rounded to a given number of digits. The ROUND function can round to the right or left of the decimal point.

Purpose:
Round a number to a given number of digits

Return value: 
A rounded number.

Syntax: 
=ROUND (number, num_digits)

Examples:

Round to right
To round values to the right of the decimal point, use a positive number for digits:  
=ROUND(A1,1) // Round to 1 decimal place
=ROUND(A1,2) // Round to 2 decimal places
=ROUND(A1,3) // Round to 3 decimal places
=ROUND(A1,4) // Round to 4 decimal places

Round to left
To round down values to the left of the decimal point, use zero or a negative number for digits:  
=ROUND(A1,0) // Round to nearest whole number
=ROUND(A1,-1) // Round to nearest 10
=ROUND(A1,-2) // Round to nearest 100
=ROUND(A1,-3) // Round to nearest 1000
=ROUND(A1,-4) // Round to nearest 10000

Nesting inside ROUND

Other operations and functions can be nested inside the ROUND function. For example, to round down the result of A1 divided by B1, you can ROUND in a formula like this:
=ROUND(A1/B1,0) // round result to nearest integer
Any formula that returns a numeric result can be nested inside the ROUND function.

Some Tips:
The ROUND function rounds to a specified level of precision, determined by num_digits. If number is already rounded to the given number of places, no rounding occurs. If number is not numeric, ROUND returns a #VALUE! error.

Compare between Round, Roundup and Rounddown functions: