code: static public function getRoundingIncrement($currency)
      {
          if (isset(static::$increments[$currency])) {
              return static::$increments[$currency];
          }
  
          return static::$increments[$currency] = static::getCurrencyBundle()->getRoundingIncrement($currency);
      }
docs: Returns the currency rounding increment.
  
  @param string $currency
  
  @return float|int|null