Im just taking a guess at why you see 100 shares sold alot.
If I read enough of the MM thing, they might get a sale for 3,000,000 @ 0.0002. They cover 3 or 4 buys 1,000,000 900,000 650,800 448,800 and have 400 shares left. Like trimings from a roast, no one wants to eat it so you feed it to the dogs. Well they can not hold on to it and someone put an all day order in for 1,000,000 @ 0.0001, they give it to him. If it happens again he might pick up another 100 or 300. He was probably the first in line, by the way. So hes just picking up the scraps and paying the fee for it. I dont think the MMs are lossing alot selling what 100-500 shares at 0.0001. What a penny? And the firm make lets say $10.00 off the transaction. I think over the day doing that, they may loss 10,20 cents and make the $10.00. Just my opinion.