Large table with totals in page footer

I am trying to create a document with a multipage table.  At the bottom
of each page I need a footer which includes some information derived
from rows printed on that page.  I am using the Table() class and rows
are variable height so I don't know which rows will print on a page.

I've looked around and can't find any way to do this.  Any pointers
would be greatly appreciated.

Regards

Tony Middleton