I used to get a little upset when I put in my order, and my server said "Anything else?" or "Is that all?"
I would think, "What, that's not enough? You want me to order more??"
But I've come to the realization that for the most part, servers don't care how much you order. What they really want to know is if they can go ahead and enter in your order, or if you need more time. It can be a huge pain if they leave you and then you have to flag them down to give them a longer order or if they ring you up in the register, and then they have to ring you in all over again because you added some additional items.
So they're not necessarily saying "that's it?? you're so cheap!" They're generally saying, "Is it okay if I go ahead and enter in your order, or are you should I wait for you to decide what else you're thinking of getting?"