Which part are you struggling with exactly? From what's written it sounds like the 'Last Year Sales'. If this is the case you could create a calculated field along the lines of SUM(IIF([SalesDate] >= 1 June 2010 AND [SalesDate]<1 June 2011,[Sales],0)).
Without seeing your data I don't know the names of your date field but this formula would sum all of the values in the [Sales] field where the sale happened between June and May - your financial year.
Once the calc field is created you could then add the [Current Year Growth Target] to this in a separate calc field.
Still Stuck on this one, so any help is appreciated. I have figured out how to calculate prior year sales:
IF [Date]<DATEADD('month',-12,#June 1, 2011#) THEN Null
ELSEIF [Date] > DATEADD('month',-12,TODAY()) THEN Null
Now I need to take that calculation and add it to this year's growth targets to get an absolute target value. When I sum the parts together, it totals correctly but I need the calculated field dates to display in the current fiscal year.
I basically need to time shift last years sales into this year and then add the growth on top, so that for instance January 2012 Target Sales = Jan 2011 Sales + Growth Target. All I get is last year sales still displayed in last year's cell - so it needs to somehow be offset.
Hope I am making sense ....