Sharebuilder. This is my 1st broker. Scottrde second (right now) Sharebuilder is restrictive of which pennies you can by which kind of gets old. But I picked up RSDS all last week. 3 times to be exact all under .01
I don't know why sharebuilder is so restrictive but RSDS is available which is more than I can say about 75% of the pennies imho. GLTA!