Αυθεντικό κείμενο - Ιαπωνέζικα - Expressions used at work in a convenience store

Nice to meet you.
I am working in convinience store as part-time worker,so i certainly must serve forgien customers at register once or twice at work.
I try to serve them in english,I serve german customers,but many english words could not be out of my idea at that moment.

So i would like to learn expressions used in work in convinience store...

1.I scaned this merchadise twice by mistake...
could i scan it one more time to remove it?

2.Excuse me,I forgot to give the 50 yen discount for this. I'll do it over,really quickly.

3.Would you like the chopsticks in the※bag?
※The bag is plastic shopping bag in this context.

4.The bathroom is the beyond the siver door near the frozen food counter.

5.Your change is 290 yen.Thanks for coming...

6.Would you like the hot drink in a separate bag?

7.Would you like the detergent in a separate bag?

P.S.
I must have served those who do not speak english at resiter.
I could not serve them(i think,chinese or korean?) very well...so i thought i have to learn these phrases in chinese or korean because there are many people of chinese and korean in japan.
So could you,chinese and korean people help me?
If you can up-load how to pronunce it,i appreciate you.
(Please write in standard dialect with which people from any region,fujian,chang-hai,hong kong...Jeju-d,Anyan...can understand.)

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