Curious … so I read that as- you bought a product that as part of the settlement of the debt you were offered the option by the vendor of the product to donate up to 10$ to some charity by rounding the final cost of the product up to the next 10$?
Total price of order: 152.02
You got a 30% discount equal to 45.61 bringing the total down to 106.41
You got a further loyalty discount of 10.00 bringing the total down to 96.41 - still just for the purchase
Rounding up to the next 10.00 for the charity donation added 3.59 - the rounded up total now 100.00
Of that 100.00, exactly 10.00 was the GST component (inclusive), so the GST Exclusive amount is 90.91
Or to put that another way:
GST Inc GST Ex
Order $152.02 $138.20
Discount (30%) $45.61 $41.46
Loyalty Discount $10.00 $9.09
Total Due (Excl Donation) $96.41 $87.65
Donation $3.59 $3.26
Total Due (Incl Donation) $100.00 $90.91
Saving $55.61 $50.55
So all the numbers they are using are GST inclusive ie have a GST component, therefore you paid GST on the $3.26 donation of $0.33 making the GST inclusive donation $3.59 … The saving is the order amount minus the total due excluding the donation.
Note I am not an accountant … yes, somewhat confusing - not sure I’ve got it right. I’d welcome someone with a clearer head at this time of night (or at any time) to correct my attempt …
I didn’t think charity donations attracted GST and I’m not sure I’ve ever seen the words ‘Tax Invoice’ on a pure donation receipt.
More info here from the ATO …
The following page also looks deceptively helpful:
The type and status of the charity seems to have significant bearing, along with a number of other possible considerations …