I wouldn't expect it from any of the discount houses. Only time I've ever gotten anything close to a sell at the ask or a buy at the bid were when I used the full service houses, even then I'm not certain I could have done so with pennies. In my experience fills only occurred when the bid/ask "moved" to my price.
Now if I had a direct line to a MM or Floor specialist...
Not all brokers are like that. Most take the spread and charge a commission. My full service broker will represent me on the bid or ask. I have to call or fax the order in though. My online broker will not represent me on the bid or the ask. If I buy, I buy at the ask. If I sell I sell at the bid. So if I am buying into a penny stock, I usually go through my full service broker. On pennies, you can sometimes pick up 20-30% easy. But if I am trading a high volume NASD issue, I go with my online broker for speed of execution.