Hi @Lakna K 

If your inventory part has inventory valuation method other than weighted average then the additional cost will be posted to variance account when entering invoice.

If your valuation method is weighted average but invoice consideration other than transaction based then again the additional cost will be posted to variance account when entering invoice.

If valuation method is weighted average and invoice consideration is transaction based then the additional cost will be posted an addition to inventory value when entering invoice. 

Hope this helps

Thank you so much, this explains well!