You may add the money_formatter key to your config/shopr configuration file:
/*
* The money formatter class. You may provide your own class here, just make sure it extends
* the default Happypixels\Shopr\Money\Formatter class.
*/'money_formatter'=> Happypixels\Shopr\Money\Formatter::class,
However, this isn't necessary if you don't plan on using your own formatter.