Selling leftover fractional shares from covered calls

I've been running a strategy in my Roth to sell cash secured puts to get into positions of stock at a good price, reinvest dividends while holding, and sell OTM covered calls against it to generate income until the shares are called away. If I want to get out I'll just move the strike closer to the money to squeeze premium from it.

It's been working well enough, but it leaves fractional shares left over when a lot has reinvested dividends. Schwab won't let me sell my .5191 shares of MDLZ (Gives an invalid quantity error), so it looks like I'm stuck with this $20 position in my portfolio. Kind of funny but annoying.

Is there some other way to sell fractional shares? Going forward, should I just not reinvest dividends? I'd rather not have a long list of tiny positions clouding things up in my account. Thanks for reading this far.