I used to do that much, I was up over 2m for a few month last year. I have since made some serious efforts to move this number down and my averages lately are about 400-700k a month (which doesn't mean that I don't have half million share days (hours)). Lately, while I still scalp, I spend most of my time researching microcap companies and buying lots of them instead. The taxes are much better for me if I hold something for a few years which is something that I never considered before. Besides, I'd rather own 1-3% of some company that goes up a few thousand percent than scalp myself brainless all day long and just pay the taxmen and brokers.
Last year I paid over 200k in commissions I belive. It was steep. I'd rather not say how much I made, but it was in the low 6-figures range. I think my best month was sept/oct. I had one 60k day (day the markets bottomed I bought like 75k shares moo that morning and sold them out all day/week long). I still finished the week only up like 20k. That 2 month period I made about 60k or so on MHX and LHO together. I think that at one point i had over 50k shares of the two stocks combined. I got the bottoms on both stocks and my buys were the low ticks in each. I don't know if that answers your questions. Do you have anything more detailed.