it breaks it down, it ends up being a penny or so, but the fees are factored into your stop-order buy/sells, so that if your market order goes through at a certain amount of money, that's what you get it for.
I've watched my Robinhood orders and compared them to Google finance at the time of a purchase or a sell, and they usually are bought for a few cents higher than the posted value on Google Finance and they always sell for a few cents less than the posted value.
Which is why I use stop-limit orders with a tight spread to control the exact amount it costs.
I did play with DWTI and held it overnight before. When I got the prospectus, it said that a certain percentage fee will be charged every day I held it. I haven't seen that fee charged to me yet, so I'm not sure how that one will play out.
But basic NYSE stocks are fairly straight forward.