Duty Charge as percentage of Item Price Not Working

We want to apply duty as a percentage of the item price in sales orders, but Oracle is only allowing fixed duty amounts. Percentage-based duty is not being calculated.

We are trying to apply duty charges as a percentage of the item price in sales orders.

For example, if the item price is $45 and duty is 10%, the system should calculate and apply $4.50 automatically.

When we set up the duty as a percentage, it is not getting calculated in the sales order.
But if we set a fixed amount (like $4.50), it works correctly.

What We Expect:
The system should calculate duty automatically based on the item price and the percentage we set.