Taxes vary by year, make, model etc.
Rule of thumb is to use 35-50% of its current value as the amount needed to get it in to satisfy duty, taxes, ITBIS, first placa.
Five year rule is not applicable in this case, assuming the semi is over 10,000 pounds GVW. Vehicles over 5 tons are allowed in up to 15 years old.
There are exceptions to this rule, both as to weight and taxes if, for example, the vehicle is imported for the purposes of a road construction project, tourist project etc.
Hope this was helpful.
Respectfully,
Playacaribe2