Even though you are buying three of one thing, they are each an 'item". As @FelskyNY was saying, they should ring up $9.99.
When it is saying limit of 1 of each coupon type per item. They are saying you could combine a store coupon with a manufacturer coupon on each, but this particular TC is a MQ, so you can only use one or the other per item.
If you got three of the unisom, you could use 2 of the PQs and the one TC. so, $9.97 x 3 = $29.97 less $8 TC less $16 PQ ($8x2) = $5.97 OOP, and you get the $5 GC.
Another interesting thing about Target math when earning a GC.
It looks like they spread the GC earned amount across participating items in your receipt, deducting the respective percentage from each item to assign a return value. That reduces your taxable obligation as well on all GC earned.
For example, IN has 7% tax, so I save 35¢ tax on the transaction since it reduced the $19.98 by the $5 GC earned, so I am only taxed on $14.98.
So it ends up being:
$9.99 less $2.50 (1/2 of GC eared) = $7.49 each X2 = $14.98 + tax = $16.03 less $8 TC less $8 PQ = 3¢ + $5 GC earned (to offset the same $5 taken off earler) = $5.03 due (and earn the $5 GC)
So in the end, I truly only paid 3¢ even after tax
(am I the only one who really enjoys the oddities of how the calculations are all done on non-standard situations?)