HELP: Changing Dates To FY (fiscal Year) And YTD (year-to-date) Values

I have a huge table with transaction dates. I need to slice and dice
this data (sum, %'s, etc), but group by FY. Our fiscal year is from
7/1 thru 6/1.

For example:
1/8/2004 = FY 2004,
8/12/2004 = FY 2005,
2/3/2006 = FY 2006

THEN . . . . I need to also isolate certain periods, for example July-
March for YTD (year-to-date) analysis and compare YTD of 2006 with that
of 2005.

What do you suggest? Many thanks.

Mehran