Supplier/Calculator/SupplierOrderCalculator.php
private function calculatePaymentBase(SupplierOrderInterface $order)
    {
        $base = $this->calculateItemsTotal($order) + $order->getShippingCost() - $order->getDiscountTotal();

        $currency = $order->getCurrency()->getCode();

        return Money::round($base, $currency);
    }
private function calculatePaymentBase(SupplierOrderInterface $order)
    {
        $base = $this->calculateItemsTotal($order) + $order->getShippingCost() - $order->getDiscountTotal();

        $currency = $order->getCurrency()->getCode();

        return Money::round($base, $currency);
    }
Calculates the supplier order base.

@param SupplierOrderInterface $order

@return float