Why would they give you 150 for a bill of 100

You would just hand them back 50 before you rung it up

Yes its fine

Your employer checks the amount in the register against sales. People caught thieving (which is what you'd be doing) get fired or get the cops called on them.

the customer can make a false complaint that he paid too much.

The final total of the money is what counts. You recorded the amount owed, that's what the register totals will show.

probably not - depends on the store accounts system and stock control

Modern tills know how much was in the till when you started , what transactions have been done and therefore how much should be in at the end, and also whats been sold during the day (for stock control)

(thats why a lot of stores scan goods, not only is it quicker than entering by hand ,it also gives the price and what the item is at the same time (so it can be recorded and printed on the bill) thus enabling easy cross referencing of sales, accounts,and stock control (restocking) automatically

you may notices that sometimes when people at the till change over its not just person A leaves and person B takes their place , both do a number of things before the leave/take over- Part of this is to "tell" the till that they are leaving and enter their ID, the person taking over then" tells" the till they are the new operator - This is so the till can record when each operator is responsible for the till)

If the machine has added up the total of goods bought to 100 then you will have 50 too much in the till at the end of the day cos the amount in it will not correspond to the items sold

if you dont tell anybody whats happened so they can correct it there is good chance you could be fired (WHEN you should tell somebody should be in the store operating procedures- they may require to be told while the customer is still there,)

cos somebody will have to work out which is-wrong -

the goods the till thinks has been sold were those actually sold? (ie the till said you sold an item A at 60$, but recorded it as item B costing 10$

or the amount charged for the goods sold was incorrect? (ie you sold an item that the till said was 60$ on the bill but recorded it as costing 10$)

either way that could be a lot of work if its a busy store)

even worse- if you take out the excess 50 to balance the till you could be charged with theft

Yes if every thing adds up then you should be okay, just let the manger know that you entered the wrong amount but gave the correct change back to the customer.

Yes as long as you give the right amount back you are fine

Yes because as far as the register knows they paid you 200 and you gave them 100 back.