Hi Bill,
You could use the setDataSource() method. In this case, the following script would need to be executed on the click of the Top 5 Customer button:
CHART_1.setDataSource(DS_TOPN);
where CHART_1 is the name of the chart you want to swap out, and DS_TOPN is the Data Source Alias of the Data Source having the Top N customers.
Another way of doing this would be to use different charts, and swap their visibility on the clicks of different buttons.
Hope this helps.
Regards,
Anuraag