Tax amount not saved with the order after payment

[al_foto]

I'm having a very strange issue with version 1.5.6.2:

 

The tax amount is not saved in the order database after the payment with Paypal. If I select bank transfer for payment the order is fine and taxes amounts are saved, also if I create an order from the cart in the backend and confirm Paypal payment manually the order is fine, but if I make a real payment for the order the taxes amount is not saved. 

 

The taxes are calculated fine in the cart, also the Paypal payment includes taxes, it's only that the amount is not saved with the order and therefore the order confirmation email doesn't include any tax and total paid is without tax. 

 

Please, I need some urgent help to solve this issue because all emails are sent with a wrong total paid amount if taxes are applied.