Will Petco sell a pet to a minor?

Hey I'm 15 years old and my parents have moved out for a few weeks/moths; my grandma is taking care of me while they're gone. My parents told me if I wanted I could buy a small pet for myself (like a rodent or a bird). I decided to get a hamster and I already have a cage and everything, but my grandma won't go with me to Petco; she has nothing against the pet, she just doesn't want to move her ***. So I'm wondering if I could go alone and get the hamster. Is it against Petco's policy to sell a pet to someone underage?