Preheat oven to 375°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.
Arrange tortilla chips in single layer on 2 lightly greased foil-lined shallow baking pans, overlapping chips if needed to cover bottom completely. Top each pan of chips evenly with meat mixture and cheese.
Bake both pans on separate oven racks 5 minutes or until cheese is melted.