When senders ship items form the US they have to complete a Custom's declaration form on this there are two tick boxes, one for 'gift' the other for 'merchandise'.
Gift can be used for any item with a 'declared' value of up to 50 US Dollars, and for any products purchased new the shipper is supposed to tick the merchandise box.
But,....one other thing to bear in mind; even if the 'gift' box is ticked, if the item is shipped from a business address with a company name then Customs will be alert to checking the goods and craging you Duty and VAT.
As a tip, what I normally do is have items sent to either family or friends and have them open items bought new, including the retail packaging, remove any invoices, and then re-package and mailing using their personal mailing address as the sender reference.
They must remember to tick the 'gift' box though!
For valuable items you must also weigh up the risks of sending something worth more than 50 US Dollars via this system.