Does anyone have any idea what was going on today? At exactly...

Does anyone have any idea what was going on today?
At exactly five minute intervals all day, there was a string of piddly little orders at 16 cents... until at 2:38pm one came in at 15.5 cents.
It was INSTANTLY followed by an apparent single order for 50,000 shares at 15.5... where the price remained for the rest of the day until a final order at 16 cents just before close.

Two questions:
(i) Who was doing what? (Obviously testing price, but...)
(ii) How does one avoid brokerage fees on all those piddly little orders? Is the bookie also having a bet?

Any ideas, anyone?