Q: Do I have to pay taxes if I am a lebanese buying a macbook pro from a US apple store ?

I assume that you will be purchasing the MBP in a USA Apple store.  You will have to pay whatever state/local sales taxes the are applicable where the store is located.  The only state that does not have a sales tax is New Hampshire.

Ciao.

There is no break for non-US nationals, every consumer must pay the State Sales tax. The prices shown are for the goods only, and tax is ADDED to the total when you check out. The tax rate you pay is the State where the goods are effectively delivered. If you buy it in person in New York, or buy from a store in New York and have the Mac delivered to an Address in New York, you will pay New York State tax (and New York City tax).

These taxes are added to your invoice and are not optional. The state has no leverage to collect the tax later. You are not leaving yourself vulnerable if the Vendor does not charge you the tax. If the vendor does not collect it, you do not owe it, and there is no revisiting that issue later.

There is a gray area in the law when you take delivery in a different State, such as by mail order. At the moment, some mail-order vendors are only charging and paying taxes in states where they have a "presence" -- a store or an office or warehouse. So if I buy from most vendors in New York, they will ship to me in Massachusetts, they do not charge me tax.

Apple and Amazon and a few other large vendors have yielded to enormous pressure from States to collect tax for every state that requires it, and they do.

And Oregon

Ask your country of residence about import and other taxes on products bought offshore. We have no idea what your government's taxing policies are. And, you will pay sales tax when you purchase the computer unless it is from a store in a state with no sales tax.

A new computer in a box will always have to pay the import duty as new goods. It could be argued that computer you are carrying and using is not new, and should not require you to pay duty as new.