Pivot Table

I'm creating a pivot table, but the data in the piviot
table cells are rounded up. I have created a worksheet
with the time format (custom) as m:ss.00 This shows
correct in the cell as say 1:34.96 However in the
function bar it is rounded up to say 1:35 also in the
pivot table it shows the same (rounded up) how can I get
the cell in the pivot table to reflect the same as the
worksheet cell.