Select number of rows to display in a grid in SSRS report

Use below expression on the new parent group to limit the number of records to display on SSRS report

=CEILING(RowNumber(Nothing)/10) 

Follow below link on how to do this exactly.

http://www.sqlchick.com/entries/2010/9/11/displaying-fixed-number-of-rows-per-ssrs-report-page.html