Preheat oven to 400°F. Brown meat in large skillet on medium-high heat. Drain fat. Stir in beans, tomato sauce, chili powder, cumin and oregano. Bring to boil. Reduce heat to low; simmer 5 minutes, stirring occasionally.
Spoon meat mixture into taco shells. Arrange tacos standing up in 13x9-inch baking dish. Sprinkle with cheese.
Bake 8 minutes or until cheese is melted and taco shells are warm.