I have 3 hamsters and a newly acquired baby corn snake. None of which are in tanks, lol, but they would all do OK in something that size. The corn snakes are known to be docile with regular handling, but will eventually need a larger hab. I have my little "guy" in a 15 gallon terrarium and he seems to be having a blast climbing around the driftwood and plastic plants I have in there.
The hamsters are Syrian, but I would recommend a dwarf hamster for a 10-15 gallon tank. Chinese dwarfs are really cute, love to dig in their bedding and do ok in small groups.
Hope some of that helps.