Try this:
1. Create a formula that will count the number of records as they print. I'll call this {@RowCount}.
2. Go to the Section Expert, click on the formula button to the right of New Page After (DO NOT check the checbox!)
3. Add something like the following formula:
{@RowCount} in (15, 25, 45)
This should give you the page breaks you're looking for.
-Dell