There's no setting. However, things have changed. Selling stuff like arrows one at a time is not really the best way to go about things. Selling single highly expensive items is better. Unlike in Oblivion, the value of an item affects how much your speech levels. With 4 items to equip that each raise alchemy +25%, it's possible to make potions worth 3000 or more, and selling those levels speech MASSIVELY.
So if you're low level and thus not coming by a lot of high value loot to sell yet, alchemy is actually a really good way to level speech. As is enchanting since you can make stuff worth quite a lot with enchanting.
I am snazzier, hot, hot rant. Warily slight as. Croak rush, OK? Weirder, almighty make out. ::)