The missing 2 cent
And I still couldn't find the results. It is rather hard to simulate the whole calculation process. Too many numbers and too complicated. It would be easier to just deduct 2 cent from my salary to pay back to customer. No, deduct $1 from my salary and save me the trouble.
It is no long cost effective judging by the effort spend by me investigating this 2 cent issue. My monthly salary, if divided to derive my hourly pay is many many times higher this that 2 cent. It is just not cost effective to do so.
But I still need to find out why the difference of 2 cent and let customer know. Its not the money, but the accountability of the system. We must proof to the customer that its not a bug but just different way of calculation that causes the difference of 2 cent.
Its the creditability of the system. And that is worth more than a million dollar.