Automatic discount on quantity based on unit price ?

Hello,

Is there a simple way to have a grid of unit price for a product by quantity, for example :
for an order between 50 and 100, the unit price will be 0.80€
for an order between 101 and 200, the unit price will be 0.50€
…
And the good unit price would be automatically applied depending on the quantity selected by the user ?

And can’t see how to achieve that with WooCommerce.
Thanks in advance for your answers.

http://wordpress.org/extend/plugins/woocommerce/