You can create a running total of records within a group {#cntwingrp} by using the running total editor. Select a recurring field, e.g., {table.id}, count, evaluate for each record, reset on change of group (Department).
Then you can go to the section expert (format->section)->details and either force a page break after a certain number of records by going to "New Page After" and entering a formula in the x+2 area:
{#cntwingrp} = 25 //substitute the number where you want the page break
Or, you could suppress records greater than a certain value, if you only want to show the first n records, by going to "Suppress" and in the x+2 area entering:
{#cntwingrp} > 25 //Substitute your number
You might get a better response if you explained the problem more specifically.
-LB