Math.Round Method (Double, Int32)
Rounds a doubleprecision floatingpoint value to a specified number of fractional digits.
Assembly: mscorlib (in mscorlib.dll)
Parameters
 value

Type:
System.Double
A doubleprecision floatingpoint number to be rounded.
 digits

Type:
System.Int32
The number of fractional digits in the return value.
Return Value
Type: System.DoubleThe number nearest to value that contains a number of fractional digits equal to digits.
Exception  Condition 

ArgumentOutOfRangeException  digits is less than 0 or greater than 15. 
Note 

For examples and comprehensive usage information about this and other overloads of the Round method, see the Round reference page. 
Notes to Callers:
Because of the loss of precision that can result from representing decimal values as floatingpoint numbers or performing arithmetic operations on floatingpoint values, in some cases the Round(Double, Int32) method may not appear to round midpoint values to the nearest even value in the digits decimal position. This is illustrated in the following example, where 2.135 is rounded to 2.13 instead of 2.14. This occurs because internally the method multiplies value by 10digits, and the multiplication operation in this case suffers from a loss of precision.
Module Example Public Sub Main() Dim values() As Double = { 2.125, 2.135, 2.145, 3.125, 3.135, 3.145 } For Each value As Double In values Console.WriteLine("{0} > {1}", value, Math.Round(value, 2)) Next End Sub End Module ' The example displays the following output: ' 2.125 > 2.12 ' 2.135 > 2.13 ' 2.145 > 2.14 ' 3.125 > 3.12 ' 3.135 > 3.14 ' 3.145 > 3.14
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1