You might get lucky and not have to pay....we had a box come in once in early January and they guy told us the first box of the year was free....gift!! Not sure if that still happens....
At that time it was maybe 1 to 3 pesos a day what they charged...but be ready as depending on what was claimed as the value of the contents you might get hit with duty as well. Stand firm and tell them it was a "gift"...not supposed to have to pay duty on gifts...but that is not a sure thing anymore either.
As most have posted here not worth having boxes shipped...wait until someone comes to visit and load them up on what you need.