Hi,
Product listing in backend, you have to edit the view "product / listing" (backend template) and replace the code:
echo $this->currencyHelper->displayPrices(@$row->prices);
By:
echo $this->currencyHelper->displayPrices(@$row->prices,'price_value_with_tax');
For the cart listing in backend, the view to edit is "cart / listing" (backend template) and replace:
echo $this->currencyHelper->format($cart->price,$cart->currency);
By:
foreach($cart->full_cart->full_total->prices as $price){
if($price->price_value_with_tax == '0')
continue;
echo $this->currencyHelper->format($price->price_value_with_tax,$cart->currency);
}