Hi,
Strangely enough there is no way of doing this within Siwapp (as far as I know).
If you're happy interacting with the database here's a simple MySQL query to get all the payments made two dates:
SELECT id, SUM(amount)
FROM payment
WHERE `date` BETWEEN '2014-10-01' AND '2014-12-31' AND amount != '';
This one lists those same payments:
SELECT *
FROM payment
WHERE `date` BETWEEN '2014-10-01' AND '2014-12-31' AND amount != '';
Hope this helps