I agree with BlueZebra. I have lived my entire life in the United States and am somewhat aghast at how the tipping environment has gotten out of hand here. For a full service restaurant with satisfactory service, 15% is still appropriate in my book. 20% or so if the service is exceptional. For buffets and other self-serve situations (such as counter service/fast food) maybe a dollar or two or three if I am made to feel so inclined by the service.

In contrast, suggested tips pre-printed on the receipt of 18%-20%-22% are merely a grab for money. Restaurant employers condone this because it lowers the restaurant's requirement to pay wages directly to the employee. This is why we are seeing tip jars in such unlikely places as Dry Cleaners.

For the breakfast that you described, the $3 and change on your bill was plenty. Please don't allow yourself to be intimidated into giving more for mediocre service.
-Goat