1. Right click on Group Header that denotes the data you want to keep together.
2. Select Change Group.
3. Mark the Keep Group Together option.

If after doing the above steps do not resolve your issue, please go into each section of your report and eliminate any extra space by shrinking the vertical size of the sections.

Also you can take the Grouped data and place this in a subreport (instead of displaying in the main report for the subreport format options select the "Keep Object Together".