I’m cashing everyone out in the line so please wait
Please stand in line to be cashed out.
Cash someone out = 会計をする
Stand in line = 列に並ぶ
I’m cashing everyone out in the line so please wait = みんなに会計をするので並んで待ってください
Please stand in line to be cashed out = 会計するために並んでください。
Thank you for your cooperation = ご協力ありがとうございます!