Please Identify My Fish!

looks like a fantail to me.

yep, look like fantails to me. Those stickers at petsmart label them as being small, but small is meaning at the time of the sale. If you look closer to those stickers, it will also label the tank size needed for the fish. Yes, this tank is going to be too small for any of these guys. I would return them and get a few smaller fish, maybe cherry barbs or something like that. OR you can go and get a bigger tank.
Another point I want to make too is that usually when first setting up a tank, your tank needs to go through a break-in period or what's known as a "cycle". You can do this with fish or without, many prefer without because there is often undue stress put on the fish and some fish are weakened because of it. You can look up Cycling" in the search feature of this site and see how you feel suits you best.

Yup thats a "small"(relative to current time) fantail. In most petsmarts if you look at the tank above you can see a "large" fantail goldfish as well. If the employee was on their toes they should have informed you that smalls grow into larges! Generally these little guys get about 6" by the time they are full grown and you want to have roughly 30G for the first fish and 10G for each additional fish (i don't remember where exactly I heard that one from though...hm...). They will take roughly 8 months to a year (I think...) to reach their full 6 inches. If its within the 14 day (or whatever the return policy is) then take them back to exchange (or look at a bigger tank).

more specifically, it looks like a calico moor

and yes your tank will be to small. but alright for the moment