Firebird SQL cursor repeat last row

Question

to begin, sorry for my English. I'm starting with cursors in FirebirdSQL 2.5, writing some stored procedures for a sales register system. In this case I need to calculate the credit card's taxes that are cashed by the banks in my country from the sales that the system record. Here is the SP code:

create or alter procedure CURSOR_POC
returns (
  ID int,
  PRICE decimal(15,2),
  TAX decimal(15,2))
as
declare variable GO_ON char(1);
declare MY_CURSOR cursor for (
  select CARD.CODE, sum(SALE.PRICE)
  from CARD join SALE on CARD.CODE = SALE.CARD_CODE
  where SALE.SALE_DATE = '14.10.2015'
  group by CARD_CODE);
begin
  open MY_CURSOR;
  GO_ON = 'Y';
  while(GO_ON='Y') do
  begin
    fetch MY_CURSOR into :ID, :PRICE;
    if (row_count = 1) then
    begin
      TAX = PRICE * (select CARD.TAXES from CARD where CARD.CODE = :ID);
      suspend;
    end else GO_ON = 'N';
    end
close MY_CURSOR;
suspend;
end

When I run the SP, its execute just fine but always show the last row twice. For instance, if I run the query in a separate file Firebird give me 10 rows, but when I run the SP I got 11 rows. Any help will be grateful. In advance, thank you very much.

P.D.: I "translate" the tables and attributes names in order to make it more understable.
P.D.2: the date filter ("dd/mm/yyyy" format) in the definition of the cursor was only define to test de stored procedure.

Answer 1

I will answer myself (a professor help me in a private forum from my University).
The solution was as simple as erase the last "suspend" from the stored procedure. So that, the code should be

(...previous code...)

if (row_count = 1) then
begin
  TAX = PRICE * (select CARD.TAXES from CARD where CARD.CODE = :ID);
  suspend;
end else GO_ON = 'N';
end
close MY_CURSOR;
end