Not all product shipments charge tax and duty, it can varies depend on different factors. We always suggest you contact your local government agency in regard to tax & duty payable, as this remains with the buyer's responsibility.
Below are some tips that may help with your tax & duty payable.
1. If the declared value of the package is lower than your local tariff threshold in most cases the package will not be taxed, but false declaration is another matter.
2. The weight of the package is an important factor for the custom to determine the package is a civil or commercial parcel as they taxed differently. For a heavy parcel that might be a good idea to separate the parcel into a few small ones.
3. A large number of the same products in a parcel can be regarded as a commercial package. So please avoid using the same parcel to send multiple single products which are same or similar.
4. For customer have multiple parcels need to ship at the same destination try to send the parcel in different days to avoid they arrive at custom all at the same time.
Please note, all above information are for guidance only, and subject to your local government agency's assessment regarding tax and duty.