There has been some discussion in the past about using custom controls, even if the derived control doesn't provide any additional functionality.

Could this idea also be applied to a variable (and is it recommended)? For example, if I find I am rounding decimals a certain way many times, would it be advantageous to create a custom decimal class with a .ToRoundedString method? Would I then want to use this derived type in place of all decimal types in my application?