Calculating median and percentiles for a report in pentaho reporting 5.0.1

Hi All,

I have a scenario like need to get the following aggregation for a report.

I have a field like "cost" in report now i want to calculate the following aggregations.

I tried summary functions like sum,min,max it worked out but how to calculate the below values.
please help me in this scenario.

Average of Cost
Median of cost.
95 th percentile of cost


Thanks,

phani