In skillet cook beef (or sausage) with onion over medium heat; drain.
Remove from heat. Add tomato sauce, cheese and oregano. Mix well.
Separate crescent dough into eight rectangles, pinching seams together.
Place about 3 tablespoons of meat mixture along one long side of each rectangle. Roll up, jelly-roll style, starting with long side. Cut each roll into 3 pieces. Place seam side down on lightly greased baking sheet about 2 inches apart.
Bake at 375 degrees for 15 minutes or until golden brown.