That's a good tip for that price. :) Pretty much the minimum polite tip is 10%; if I remember correctly, servers are taxed with the assumption that they make 10% in tips, so they're actually losing money on anything less than that. For a regular meal, it's uncommon to tip higher than 20-25%, but for something very cheap, I'd rather leave at least a dollar or two than use a percentage. (Dunno if that's universal or not.)
Something to watch out for: Most restaurants will add a gratuity for large parties, e.g. parties of six or more get charged 15% automatically--presumably because they'd be especially screwed if those tables stiffed them. Anyway, it's easy to not notice and then tip anyway out of habit, and a lot of places will let you do that without pointing out the (potentially expensive) mistake.
Rambling and paranoia aside, most people use "double the tax" as a rule of thumb, since it's usually printed there on the check and doubling is easy. :) In California, that comes out to 16% plus a little, but I don't know what Washington sales tax is. Find out before using that. ; )
Way too verbose, but it's something I've thought a lot about for no particular reason.
Something to watch out for: Most restaurants will add a gratuity for large parties, e.g. parties of six or more get charged 15% automatically--presumably because they'd be especially screwed if those tables stiffed them. Anyway, it's easy to not notice and then tip anyway out of habit, and a lot of places will let you do that without pointing out the (potentially expensive) mistake.
Rambling and paranoia aside, most people use "double the tax" as a rule of thumb, since it's usually printed there on the check and doubling is easy. :) In California, that comes out to 16% plus a little, but I don't know what Washington sales tax is. Find out before using that. ; )