Discount for every 3 products added - not minimum of 3

-- HikaShop version -- : 3.4.0

I need to add a discount for multiples of 3 to a product - not at quantity 3 the discount kicks in. Our product price per unit is $12.99.

We want to set it up so that for every 3 items ordered, the price defaults to $29.99 for those 3. And then for each item thereafter it would charge the regular $12.99 until they hit another 3 items in the same order, in which case that set of 3 would automatically go to $29.99 as well.

E.G. Order of 3 items - $29.99
Order of 5 items - $55.97
Order of 6 items - $59.98

We also need each bundle of 3 to still show up as 3x separate on the packing slip ideally.

Right, but won't that kick the coupon into action at a quantity of 3 and then every subsequent addition will still get the discount ie. 4 products at the total discount instead of 3 at discount and 1 at full? I need the discount to kick in for EVERY 3 not at 3.

So we need this:
Quantity of 1 = $12.99
Quantity of 2 = $12.99 x 2
Quantity of 3 = $10.00 x 3
Quantity of 4 = $10.00 x 3 + $12.99 x 1
Quantity of 5 = $10.00 x 3 + $12.99 x 2
Quantity of 6 = $10.00 x 6
Quantity of 7 = $10.00 x 6 + $12.99 x 1

And so forth.

Ok. That's not a bad alternative - obviously we'd have to build it out to a finite level since infinite is not achievable. If we come up with a solution that works then I will post it here in case anyone else needs it.