Need Help in solving SQL QUERY

Question

I have my table data as follows

EMPID	FedTaxID	TaxType	Amount
1059	888888888	TX02	2000
1059	888888888	TX02	1000
1059	888888888	TX03	2000

I write a query to sum up the amount as follows

select SUM(Amount)
FROM
   tblTest
WHERE
   FedTaxID = '888888888'
   AND
   TaxTypeCode IN ('TX02', 'TX03')

But what i need is if TX03 exists 1 in the table i would like to add the amount multiple times means if i sum the total i will get 5000 but i would like to get 7000. If TX03 exists 1 time in the table i would like to add multiple times any idea please