The Minimum Value Insurance is a field of the freight table imported into the carrier, which works as a kind of insurance, based on the value of the products, taking into account the additional per price column. If the additional per price is less than the Minimum Value Insurance, you must consider the Minimum Value Insurance instead of the additional, and add it to the absolute value of the freight.
If the value registered in Minimum Value Insurance is $15.00, the freight will be $25.00. Since it is more than the additional per price, this is the value that must be added to the R$ 10.00 of absolute freight.
If the value registered in Minimum Value Insurance was $5.00, the freight would be $20.00 (absolute freight + additional per price), once the additional per price beats the minimum value required for insurance.