Rules from Bunco on Wikipedia:

Each game consists of six rounds, numbered one to six in the order played. Players take turns rolling three dice. One point is awarded for each die rolled that matches the current round number, 5 points are awarded if all three dice match each other, but do not match the current round number, and 21 points if all three dice match the current round number (a “bunco”). If any points are scored, the player gets to roll again, continuing to add to their score. If no points are awarded, the player’s turn ends and the dice are passed to the next player at the table. Each round ends when a player has scored 21 points, which makes rolling a bunco an instant win. The game ends when all six rounds are complete. The player with the most rounds won is the overall game winner, with ties typically broken by comparing total points scored.