A negative fee in payment method (solved)

Hi!

I have a idea: Why a payment method don't be a discount rule?
If exists a payment method without taxes for the store owner why not offer a discount?
Your thinks.

It could be tricky to implement.  Payment is the last step in the checkout process - it needs to know what the total cart amount is so that it could, for example, compute an additional fee based on cart $ total / percentage.

See discussions about negative fee and Additional Fee Plugins here

Many thanks New York!

I go to try some thing, if have success I place the results here.

The topic title has changed to a more properly.


Then...

Well, I change all "if (fee <= 0)"  to if(fee == 0),  if (rate > decimal.Zero)  to  if (rate != decimal.Zero)
and now the checkout page stay:

4 Payment method

   [x]   pagseguro  

   [ ]   check/money     (-27,50)

But still the negative fee occur over order total surely why shipping method comes before.
If have a way of place the fee over subtotal will be perfect.