Yes Snowy, you are both right & wrong. As per the ICICIDirect fee structure below, volume traded monthly determines your brokerage slab. Higher traded volume drastically reduces the brokerage charged. Initially brokerage is charged maximum but as the month is completed, the total traded volume is calculated (both legs are included), the corresponding volume slab and brokerage chargeable are fixed & the excess brokerage charged is credited back into your savings account by 5th or 6th of following month. This way the brokerage is pretty low if you trade good volumes per month. Infrequent traders or low-volume traders will definitely find ICICI's brokerage relatively high. 
ICICIDirect fee structure:
Brokerage on trades done in Margin Segment:
Total Eligible Turnover (Volume of Transaction) per month
Brokerage
More than Rs. 20 crore
0.03%
More than Rs. 10 crore and upto Rs. 20 crore
0.035%
More than Rs. 5 crore and upto Rs. 10 crore
0.04%
More than Rs. 2 crore and upto Rs. 5.0 crore
0.05%
More than Rs. 0.5 crore and upto Rs. 2 crore
0.075%
Up to Rs. 0.5 crore
0.10%
Brokerage is calculated on a per share basis and is rounded off to the fourth decimal.
SERVICE TAX OF 10.20 % of BROKERAGE will be charged additional. Earlier the service tax of 8 % was included in the brokerage charges. The service tax is rounded off to four decimals.
SECURITIES TRANSACTION TAX (STT) EQUITY - STT is calculated on the Weighted Average Price of the client for a particular day. This is also calculated per share and rounded off to fourth decimal.
STT at the rate of 0.10% of turnover will be charged in addition to the Brokerage on all Delivery Trades
STT at the rate of 0.02% of turnover will be charged in addition to the Brokerage on sell leg of all non-delivery Trades.
The final value of Brokerage, Service Tax and Securities Transaction Tax (STT) is arrived at by multiplying the per share value in four decimals with the Quantity. This value is then rounded off to two decimals. For trades done in BSE, all calculations as mentioned above are rounded off to 2 decimals.
The minimum value of the trade that would be accepted would be Rs. 500/- and the minimum brokerage would be Rs 15/- per. Service Tax and Securities Transaction Tax (STT) will be charged additional as per the applicable rate.
ICICIDirect fee structure:
Brokerage on trades done in Margin Segment:
Total Eligible Turnover (Volume of Transaction) per month
Brokerage
More than Rs. 20 crore
0.03%
More than Rs. 10 crore and upto Rs. 20 crore
0.035%
More than Rs. 5 crore and upto Rs. 10 crore
0.04%
More than Rs. 2 crore and upto Rs. 5.0 crore
0.05%
More than Rs. 0.5 crore and upto Rs. 2 crore
0.075%
Up to Rs. 0.5 crore
0.10%
Brokerage is calculated on a per share basis and is rounded off to the fourth decimal.
SERVICE TAX OF 10.20 % of BROKERAGE will be charged additional. Earlier the service tax of 8 % was included in the brokerage charges. The service tax is rounded off to four decimals.
SECURITIES TRANSACTION TAX (STT) EQUITY - STT is calculated on the Weighted Average Price of the client for a particular day. This is also calculated per share and rounded off to fourth decimal.
STT at the rate of 0.10% of turnover will be charged in addition to the Brokerage on all Delivery Trades
STT at the rate of 0.02% of turnover will be charged in addition to the Brokerage on sell leg of all non-delivery Trades.
The final value of Brokerage, Service Tax and Securities Transaction Tax (STT) is arrived at by multiplying the per share value in four decimals with the Quantity. This value is then rounded off to two decimals. For trades done in BSE, all calculations as mentioned above are rounded off to 2 decimals.
The minimum value of the trade that would be accepted would be Rs. 500/- and the minimum brokerage would be Rs 15/- per. Service Tax and Securities Transaction Tax (STT) will be charged additional as per the applicable rate.