Grouping and Row limit in SSRS
As you said you want to do this at report level here is what i can think of:
You can try reducing the value in Height section in Interacivesize property of your report according to your needs,which is set to 11in by default and shows whatever records can fit in that much space :

Note: In case you have a small database and want to show all the values in 1 page itself setting the Height value to 0 will do the trick for you. Hope this helps.