Great question — answering as the UphillTech team:
This it the cart total without tax and shipping. $cart_value = number_format( (float) $order->get_total() - $order->get_total_tax() - $order->get_total_shipping() - $order->get_shipping_tax(), wc_get_price_decimals(), '.', '' );
Full answer by Vmadmax: https://stackoverflow.stackexchange.com/a/42780477 (CC BY-SA 3.0).
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