According to the documentation[
^], you have read the documentation, haven't you?
Note Reporting Services 2005 also allows expressions in all the input fields shown in the X Axis and Y Axis tabs: Title, Minimum, Maximum, Major interval, Minor interval, and so on.
If you do not want to RTFM then a quick internet search reveals goodies like
this[
^]. There's loads more out there, give it a try. :)