Crystal Reports: Select the field value nearest to the 90th percentile value

I have a report that needs to display the 90th percentile from a list of values. I am able to obtain the 90th percentile value, using a summary option, but the value that I get isn't the exact value from the list; it is a calculated value by the summary option. So for example, the report will give me something like 150, but I know that the actual 90th percentile value from the list is 155. It's a little off as it is not an exact value from the list (again).

Is it possible to use this calculated number to select the actual 90th percentile value from the list, or the value that is close to it?