To format the decimal variable

Try this

i = Math.Round(6.1056,2);

As already given in Solution 1 and 2, the Round method of Math class explained here
Math.Round Method (Decimal, Int32, MidpointRounding)[^]
can be used as follows:

decimal number = 6.1056M;
Console.WriteLine (Math.Round(number,2));

By default the Round method uses MidpointRounding.ToEven enumeration value explained here http://msdn.microsoft.com/en-us/library/system.midpointrounding.aspx[^], which means that if the value to be rounded is 6.105 it will be rounded off to 6.10 and if it is 6.115 then it will be rounded off to 6.12 as 5 is the mid point.

If the MidpointRounding.AwayFromZero is used as shown below

decimal number = 6.1056M;
Console.WriteLine (Math.Round(number,2, MidpointRounding.AwayFromZero));

then the above values will be rounded off to 6.11 and 6.12 respectively, i.e. always the number away from zero, in other words the next higher number will be taken.