Glad you finally caught up. This has been a thing for quite some time now.

The very simple fix is to add a small handling charge of say $3 or $4 to international sales. This will slightly increase your profit margin for non-US purchases which can then be used to offset the tariff charged on US shipments. This way, the US tariff charge is spread across all of your international shipments which is far less noticeable than slamming one single shipment with the lot.

With the rather weak value of the AUD, your buyers probably won't even notice, and it shouldn't affect your sales in any way. This works for me.