How is Johnny Rockets Charged on board?

[comfixit]

On the App Jonny Rockets shows an onboard dinning price of $9.95 + 18% gratuity. When you click menu you see various items priced between $1.99 for a side of fries, $7.99 for most burgers and then a mysterious line item of $11 labeled Adult.

 

Anyways do you pay a la carte or do you get a pre-fix for a set price or do you order as much as you want room service style?

[mets123]

Depends on what class ship you are on.