Given the opponent's moves in previous rounds—paper, rock, paper, scissors—it appears that they might be intentionally countering my previous moves. However, since trying the same moves has not been fruitful, I have decided to switch my strategy in round 5 by playing paper, hoping to disrupt any predictable countering pattern he may have adopted. If the opponent expects a pattern based solely on my previous moves, this may catch him off guard. Additionally, paper will win against rock should he choose it, which could be his likely move if he's following the pattern from the earlier rounds. Thus, I choose paper for round 5.