I'm using the following formula to show pergentage discount on frontend
$sconto = 100 - ($_product->getFinalPrice() / $_product->getPrice())*100);
It's working well with > 1 € prices, but failes with this case:
- Full price 0,90 €
- Discounted price 0,86 €
- Discount (by catalog price rule): 5%
- Discount showed: 4%
I think it is a round problem, but I don't now how to solve.