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The rounding is applied for total amount amount 
of each ticket (total amount = ticket unit amount + charge fee), followed by step (3) of this scenario:
- User purchases a ticket with price 1001 COP, charge fee 7%
- Total amount to pay for this ticket is: 1001*1.07 = 1071.07 COP
- Round this total amount with rounding value 50, so total amount = 1100 COP, which is the final amount to pay
- The charge fee amount of this ticket is the subtraction of rounded total amount and initial ticket price (1100-1001=99 COP)
In this concept, rounding total amount only mentions unit amount and charge fee, it ignores other types of fee such as price breakdown, overhead, shipment fees,...