Is a 5 gallon tank big enough for 1 betta?

I've been thinking about getting a betta, so I bought a Tetra 5 gallon aquarium kit, some gravel, a heater, and java fern. I was wondering if the tank would be big enough for 1 betta? I've heard people say they need at least 10 gallons, so I'm not sure. I'd probably put a snail in there too.