Bet365's "tennis accumulator bonus" is designed to reward customers for placing accumulative bets on tennis matches. The bonus amount increases based on the number of selections in the accumulator, with a percentage of the total winnings added as a bonus. To be eligible for the bonus, customers typically need to place a minimum number of selections within the accumulator and bet on specific tennis markets. Additionally, bets must be placed with real money, and the bonus may only apply to certain competitions or matches as outlined in the terms and conditions. It's important to check Bet365's official website for the most current details, as terms can change.