I prefer not to reward good behaviour with food, but sometimes I might treat them if I feel like it. I couldn't give in whenever they want sweets even if I wanted to as I couldn't afford it. Treats don't have to be food either. They could be a trip to the park or somewhere special, or baking something together.
I like to give treats to my children. They understand why they are getting the treat, they do not misbehave if they don't get the treat, and they always deserve it when they do get it. I think I am softy by nature.