I wish to use the round() function in the math class of the .net framework class library

[C++]

Math::Round(3.44, 1); //Returns 3.4.

Math::Round(3.45, 1); //Returns 3.4.

Math::Round(3.46, 1); //Returns 3.5.

Ive tried just using the above, but the namespace specifier isn't working. Do i need to inclue a header file. I have little experience in using the .NET framework library, your help will be much appreciatec