YES you can buy and sell the same day HOWEVER, the rules are that if you buy you must pay for the purchase in full, and you can not use the proceeds of the sale to cover all or part of the purchase.
As long as the purchase is paid in full you can buy and sell all you want. You will have to address the pattern trading tag. which could force you to maintain $25,000 equity at all times in a margin account which you must open. HOWEVER penny stocks are not marginable but if you are tagged as a pattern trader you will be subject to the rules.
So to answer your question directly YES you can buy, sell, buy sell as long as you make payment in full for your purchases and such payment is made prior to the sale.
JOHN W – All trades, whether they be done in a cash or a margin account settle in three business following the trade date since the entire industry post trades as of the settlement date. A seller DOES NOT have 3 days to deliver to the buyer, on settlement date all trades are to settle and they do not settle until then. In a margin account, the broker DOES NOT have to borrow to make deliver if a stock is bought and sold prior to settlement day
from the street.