BID 0.01
BID 10000
BID 5000
BID 5000
SALE 7000 3
DEL 5000
SALE 3000 3
SALE 0.01 3
QUIT
----------
i use the following logic:
sum = 0.00
BID 0.01
BID 10000
BID 5000
BID 5000
SALE 7000 3
<=>
BID 0.01
BID 5000
BID 5000 sum = 0.01
+
DEL 5000
<=>
BID 0.01
BID 5000
+
SALE 3000 3
<=>
BID 0.01 sum = 0.02
+
SALE 0.01 3
<=> sum = 0.03
+
QUIT
sum = 0.03

Hey you've turned it all upside down!
Once a person said "BID X" it means he's not going to buy it for more! And.. where have you put BID 10000?
Here's the correct logic:

BID 0.01
BID 10000
BID 5000
BID 5000
SALE 7000 3//selling only 1 to person of 10000 <=> sum=0.01
DEL 5000
SALE 3000 3//selling 2 to 5000 and 10000 <=> sum=0.03
SALE 0.01 3//selling 3 to 0.01, 5000, 10000 <=> sum=0.06
QUIT

any more questions?:)