Here is a list of every broker I’ve tested, including those that will round up reverse splits and those that do not. While I do earn money from affiliate links from some of these brokers, I only recommend those that I personally use to trade reverse splits, and I only link to the deal that gives YOU the best sign up rewards.
Quickly, though: DO NOT USE E-Trade, TD Ameritrade, or TradeStation! E-Trade and TD Ameritrade charge a $38 fee for each reverse split. While TradeStation does round up fractional shares, if you purchase a single share the day before a split, they will charge you a $20 fee and set your account to “liquidate only.” They are not fans of reverse split arbitrage as a strategy.