I have excel file containing sales data per every month over about 10 years.?

iwant to create apivot table report to group sales data over fesical years (start at jul.1st of a year & end at jun.30 of the next year)but the defult grouping in pivot tapl is carried over a year begins at jan.1st & ends at dec.31) how can i change the year limits to start at jul.1st & end at jun.30 of the next year instead of starting at jan.1st & ending at dec.31 of the same year).