check errors for cash machine

function checkCashRegister(productPrice, cashGiven, cashInDrawer) {
  let changeNeeded = cashGiven - productPrice;
  let errors = checkErrors(changeNeeded, cashInDrawer);
  if (typeof errors == "string") {
    return errors;
  } else {
    return [];
  }
}

function checkErrors(changeNeeded, cashInDrawer) {
  let totalCashInDrawer = cashInDrawer.reduce( (total, currencyNameAndCash) => {
    return total += currencyNameAndCash[1];
  }, 0);

  totalCashInDrawer = Math.round(totalCashInDrawer * 100) / 100;

  if (totalCashInDrawer < changeNeeded) {
    return "Insufficient Funds";
  } else if (totalCashInDrawer == changeNeeded) {
    return "Closed";
  }
}