Method roundFixedAmountCoupon

public function roundFixedAmountCoupon(&$total)
{
    $app = Factory::getApplication();
    $paramsC = PhocacartUtils::getComponentParameters();
    $rounding_calculation_fac = $paramsC->get('rounding_calculation_fixed_amount_coupon', -1);
    if ($rounding_calculation_fac < 0) {
        return;
    }
    $discount = 0;
    if (!empty($total['couponcartfixedamount'])) {
        foreach ($total['couponcartfixedamount'] as $k => $v) {
            if (isset($v['discount'])) {
                if (isset($v['netto']) && $v['netto'] < $v['discount']) {
                    $discount = $v['netto'];
                    // more pieces of product - so the cart discount is divided to more pieces of products, but max to cart discount fixed amount
                } else {
                    $discount = $v['discount'];
                    // one product - whole cart discount goes to one product
                }
            }
        }
    }
    if (isset($total['dnetto']) && $total['dnetto'] > 0 && $discount > 0) {
        $dif = $discount - $total['dnetto'];
        if ($dif > 0) {
            $total['rounding'] += $dif;
            $total['dnetto'] = $discount;
        } else {
            if ($dif < 0) {
                $total['rounding'] -= $dif;
                $total['dnetto'] = $discount;
            }
        }
    }
    return;
}