Onto Prestashop 220.127.116.11, add a product into back-office with price ex.tax 20.825 €.
Add french tax + 20%
You'll see a price incl. tax set to 24.99€.
Now, order this product.
Go onto database, on order_details, and check total_price_tax_excl column.
You'll see 20.830000. It's false, it must be 20.825000.
It's a problem when you'll try to get data from webservice, rounded prices are different: 20.830000 * 1.2 != 24.990000.
total_price_tax_incl is right (24.990000).
Do a request to webservice