How is SCB fees calculated? I bought USD 2500 worth of shares and I was charge $22 commission fee.?

They are charged at 0.2% your trade value for SGX shares and 0.25% for all other markets (assuming you are a personal banking client). They are subjected to a minimum of AUD/CHF/EUR/GBP/SGD/USD 10, HKD100 and JPY1000. Minimum brokerage amount will be based on the currency the shares are traded in.

Working backwards, I assume the shares were roughly $4.4 if you bought them on SGX and roughly $3.5 if on other exchanges.

Did you make more than 1 transaction?