Modify calculations of sales in Reports

Hi!
As I understand, the following order statuses are included in calculating gross and net sales: completed, processing, and on-hold. Also, refunds are subtracted from both of these amounts (and shipping and tax costs from net sales).
Is there a way to specify what order status to include (particularly, I would like to exclude on-hold orders) and to exclude refunds? I need just to take into account completed and processing order, and the amount of refunds should not be subtracted from that. Also, if I make some custom statuses, I would like to include (or exclude) those as well.
I read somewhere that there is a plug-in for this, but I couldn’t find it.