Actually the website does say 10%, this is right from my planner. This is illegal in most states, you can't advertise something and then not offer.
DETAILS
Enjoy the ease of paying one flat price for your spirited beverages over the entire length of your cruise. Now, that’s something to cheer about! Save 10% by purchasing before you sail.
Cut-off for pre-purchase is 11:59 PM the day before embarkation and 9:00pm EST through call center. Additional restrictions apply, see below.
CHEERS! INCLUDES:
All spirits (including cocktails), as well as beer and wine by the glass with a $20.00 or lower menu price
Sodas, Zero-Proof frozen cocktails, energy drinks, specialty coffee, hot tea, 500ml bottled water and other non-alcoholic bottled beverages
Packaged water in the Dining Room and Specialty Restaurants
25% discount off the menu price for any spirit or wine by the glass above $20.00
25% discount off the menu price for wine and champagne by the bottle
25% discount off beverage seminars and classes