Discoverer Condition/Filtering to retrieve limited records

This I hope would be easy for any oracle/discoverer geniuses. O.K. even a regular user, but not me.

I retrieve customer records and have the data sorted by a particular column with numeric data.
I am retrieving by period year so, each of my customers has about 5 or 6 rows then totals the data.
I have many customers and way too much data. My dilemma is I want to only retrieve the first five or ten customers. Is there any way to set a condition where only say the first 20 rows of data will retrieve rather than hundreds of rows with hundreds of customers? I was trying to get a clean break where the results will show just the top five customers. The field that separates each customer would be a change in the customer name or a text field the says project total in one of the columns of information.

Thanks in advance for any insight or help

--
John