After checking the European and US sites it appears that the fees are the same. I put below the Tiered prices, which are the same in both places. I hope this is what you meant.
United States - Tiered
VOLUME (PER MONTH) 2, 7, 8
IB COMMISSION PER SHARE
US STOCKS, ETFS, ETPS AND WARRANTS
MINIMUM PER ORDER
MAXIMUM PER ORDER
<= 300,000 Shares
USD 0.0035
USD 0.35
1.0% of trade value
300,001 - 3,000,000 Shares
USD 0.002
USD 0.35
1.0% of trade value
3,000,001 - 20,000,000 Shares
USD 0.0015
USD 0.35
1.0% of trade value
20,000,001 - 100,000,000 Shares
USD 0.001
USD 0.35
1.0% of trade value
> 100,000,000 Shares
USD 0.0005
USD 0.35
1.0% of trade value