By default, .Net rounds mid-point number to nearest even number:
var roundedValue35 = Math.Round(3.5);
Console.WriteLine("Default Rounded Value for 3.5 is {0}", roundedValue35);//print:4
var roundedValue45 = Math.Round(4.5);
Console.WriteLine("Default Rounded Value for 4.5 is {0}", roundedValue45);//print:4
var roundedValue325_1 = Math.Round(3.25, 1);
Console.WriteLine("Default Rounded Value for 3.25 with 1 is {0}", roundedValue325_1);//print:3.2 You can change this default behaviour by passing MidpointRounding.AwayFromZero to the method as below:
roundedValue35 = Math.Round(3.5, MidpointRounding.AwayFromZero);
Console.WriteLine("Rounded Value by passing MidpointRounding.AwayFromZero to the Round method for 3.5 is {0}", roundedValue35);//print:4
roundedValue45 = Math.Round(4.5, MidpointRounding.AwayFromZero);
Console.WriteLine("Rounded Value by passing MidpointRounding.AwayFromZero to the Round method for 4.5 is {0}", roundedValue45);//print:5
roundedValue325_1 = Math.Round(3.25, 1, MidpointRounding.AwayFromZero);
Console.WriteLine("Rounded Value by passing MidpointRounding.AwayFromZero to the Round method for 3.25 with 1 is {0}", roundedValue325_1);//print:3.3