In SQL Server Reporting Services you can add a page break after a desired amount of records. Here is how you do it.
1. Add a new Row Group and give it a name.
In our example we named our group:
LimitNumberOfRowsPerPageGroup
2. Go to the properties of the Row Group.
3. Use the following expression to group the row on:
=Floor((RowNumber(Nothing) – 1) / 250)
In this example, 250 is the number of records we want per page.
4. On the Page Breaks tab, check the following:
‘Between each instance of a group’
‘Also at the end of a group’
Go ahead and run the report.
You should now have 250 records per page.
SoCalSQL - Jeff Prom's SQL Server Blog 
what if there are row groups exists already in the report
It returns back only on row, what I am doing wrong?
I find what was wrong, when I use the expression(“=Floor((RowNumber(Nothing) – 1) / 250)”) it does update the sorting expression as well to =Floor((RowNumber(Nothing) – 1) / 250), if you face the same issue, delete the sorting expression and you should be fine.
Thanks
Even I have the same question as NIsh
If you already have a row group, you would simply add another row group that would only be used for the number of records.
This was really helpful. Do you have any ideas on adding two page breaks? I am working with duplex paper, and if the page goes beyond the second page, a prior customers info will be on the back of the next customer record. I have tried everything to get it to work. Any Ideas? Thank you in advance
I tried your solution and the following happens. If you have a grouping below the Limit Number grouping, it counts all records in the child group, therefore it is not consistent in the number of rows it displays. Also, for some reason, it shows duplicate rows. Help please?
Thank you in advance.