Do keep in mind, though, that water parameters are much easier to maintain in a larger tank--say 20-30 gallons instead of just 10 (also bear in mind that the actual volume of water the tank holds will be reduced by displacement from live rock and sand, so a 10G tank might actually hold only 7-8 gallons of water).
Also, the smallest species of clownfish (perculas) will still grow to be about 3" long or so. They may not roam like a tang, but they're still pretty active and will appreciate a little extra space.
Especially if you're just starting out, I really would advise getting a 20- or 30-gallon aquarium instead of a very small one. People often think a very small tank will be easier to maintain, but the opposite is true--it's easier to keep a larger system stable, which is very important to the health of your animals. A larger aquarium may also be big enough to allow you to keep some corals and one or two (at the most!) other very small fish like gobies.
