Math.Round Method (Double, MidpointRounding)
Rounds a doubleprecision floatingpoint value to the nearest integer. A parameter specifies how to round the value if it is midway between two numbers.
Assembly: mscorlib (in mscorlib.dll)
Parameters
 value

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

Type:
System.MidpointRounding
Specification for how to round value if it is midway between two other numbers.
Return Value
Type: System.DoubleThe integer nearest value. If value is halfway between two integers, one of which is even and the other odd, then mode determines which of the two is returned.
Exception  Condition 

ArgumentException  mode is not a valid value of System.MidpointRounding. 
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, MidpointRounding) method may not appear to round midpoint values to the nearest even integer. In the following example, because the floatingpoint value .1 has no finite binary representation, the first call to the Round(Double) method with a value of 11.5 returns 11 instead of 12.
using System; public class Example { public static void Main() { double value = 11.1; for (int ctr = 0; ctr <= 5; ctr++) value = RoundValueAndAdd(value); Console.WriteLine(); value = 11.5; RoundValueAndAdd(value); } private static double RoundValueAndAdd(double value) { Console.WriteLine("{0} > {1}", value, Math.Round(value, MidpointRounding.AwayFromZero)); return value + .1; } } // The example displays the following output: // 11.1 > 11 // 11.2 > 11 // 11.3 > 11 // 11.4 > 11 // 11.5 > 11 // 11.6 > 12 // // 11.5 > 12
Available since 4.5
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1