If you scalp all day and you would rather bid a little over .05 instead of going all the way to .06 (say to get out of a short), that penny can add up. One cent on five thousand shares is fifty bucks............If you're doing this all day and you're only really trying to make five, ten, fifteen, twenty - five cents.....whatever, this stuff adds up. Nothing wrong with being efficient.
Put in bids/offers the opposite way you want to trade, then when they jump in front of you - pick them off. You do run a risk of getting hit yourself, but in a slow mkt this can work pretty well.