This post is just as a reminder to the msdn links and for those that are not aware.
There are a number of built in methods that can be used on SSRS reports. Such things as formatting numbers, getting current user etc.
These can be used in the expression in the design of the report.
Here are some examples:
=Microsoft.Dynamics.Framework.Reports.BuiltInMethods.ToDisplayStringAmount(Parameters!AX_RenderingCulture.Value, Sum(Fields!Balance02.Value), true)