Trim excess fat off round steak and cut into 1" pieces. Combine with remaining ingredients except rolls in 4-6 quart slow cooker. Cover and cook on low for 10-12 hours, until beef is very tender.
Remove cooked beef from mixture in crockpot.
Coarsely shred using 2 forks and place in large saucepan. Add 2 cups sauce from crockpot to meat and stir to blend well. Keep warm over low heat while serving into sandwich buns. 20 sandwiches