I need to change the price for different products based on the classifications (subitem of) each product. Is that possible?

Example: Change the price of all the Laptops by increasing 6% from the cost. Change all the printers by 8%. Or even change subitems of subitems... Change Epson printer by increasing 4% change HP printers by 10%.

Yes you can update multiple items based on whether it's a subitem. For example for all subitems of Cabinets :-

SELECT FullName, SalesPrice FROM ItemInventory where ParentRefFullName = 'Cabinets'

I would run the following UPDATE statement to increase the price by 6% :

UPDATE ItemInventory set SalesPrice = (SalesPrice * 1.06 )
where ParentRefFullName = 'Cabinets'

And the Sales Price is increased:

SELECT FullName, SalesPrice FROM ItemInventory VERIFY where ParentRefFullName = 'Cabinets'

Note: I used the VERIFY tag here to force a reload of the new prices into the optimized table. Use the VERIFY tag only if you don't see the price change.