Gift With Purchase

If the gift is part of an order, then I would post it to a COGS TYPE account you can create in the chart of accounts named COS, Cost of Sales.

COGS is technically only used for the cost of inventory sold when you file taxes.  While you can post it there, it makes income tax time a little more complicated

You can create a separate Expenses Account as "Sales/Business Promotion","Dealer Schemes" or as suitable and these will show as indirect expenses in PL