Transactional value means value for which a manufacturer sold good to wholesaler then why include sales & advertise exp.in definition of transactional value

Suppose Manufacturer wants to charge 100000 from wholeseller

Excise will be 12,5% of 1000000=12500

Manaufactuer can do Tax planning and prepare bill as follows

Sales Price  80000

Advertising Charges 20000

Excise =12.5% of 80000=10000

Hence Tax Saved =12500-10000=2500

To avoid such tax planning,Govt has said that Transaction Value includes such advertising charges

Excise in this case will now be 12.5% of (80000+20000)=12500