Why is the billed shipping cost lower than our standard rate?

We charge $9.95 AUD for standard shipping however in the last week all of our invoices say customer shipping cost has been charged $9.05 AUD. Can you please help?

It appears that $9.05 AUD is without GST. If you add GST, it becomes $9.95 AUD.

GST is ticked on my settings. It appears that the order confirmation email received by customers does say 9.95 however at our end it says 9.05