Query to return zero if nothing exist

i have a table With currency, paymenttype and invoiceamount. I have to write query to get currency , paymenttype and total invoiceamount made. This is preety dimple with group by But actually i have three payment typr 0, 1 ,2 And data in table is

    Currency.  Paymenttype invoice amount
    Aaa.        0.           100
    Aaa.        1.           200
    Aaa.         1.            50
    Bbb.         0.           150
    Bbb.         1.           100
    Bbb.          2.          100

My query is Select currency, paymenttype,sum(invoiceamount) as total from table group by currency, paymenttype

Result

      Currency  paymenttype total
      Aaa.       0.          100
      Aaa.       1.           250
       Bbb.         0.           150
       Bbb.         1.           100
       Bbb.          2.          100

But what i want is as Aaa. Doesnot have 2 paymenttype is should also show a row with 0 value like below.

      Aaa.      2.     0

How to do this?

Thanks in advance