This is the text I just got from Zecco announcing their increased fee structure as of 30 March 2011. Indeed for stocks under a dollar they're charging $6.95 per trade. I'll be shopping for another broker, they're not worth the increase.
Starting on March 30, 2011, our new commission rates will be:
* Equity trades: $4.95 per trade*
* Options trades: $4.95 per trade, plus $0.65 per contract
For stocks and ETFs priced under $1.00, online trades are $6.95.
With this change we are no longer offering 10 free trades per month. As before, there are no minimum balance requirements or inactivity fees to open or maintain a Zecco Trading account.
To answer your question: They've never charged an extra fee for large orders, but I wouldn't put it past them now.