The advice given here on fishlore is only our best advice for the health and happiness of the fish you are keeping.
Shawnie has given advice that fits the profile on fishlore for goldfish. You can view that at:
http://wwwlfishlore.com/Profiles-Goldfish.htm
On the first point on their care it states a minimum of 10 gallons per fish. If you go by the article Shawnie found for you, it would be more like 60 gallons just for the juveniles you have! I think the store person who sold you these fish did a disservice to you and your fish by giving bad advice.
The rule we go by is to size the tank as it needs to be for ADULT fish. This way people don't buy more fish than the tank they own can support. This is because often fish grow faster than the owner wants to upgrade tanks.
If you don't choose to follow these suggestions it is certainly your right. We will continue to give the same advice, and hope before your fish have problems you will be able to upgrade. If you have any other questions feel free to ask....