Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$15.49	9.303%	$16.931	$16.93	$16.95	$16.90
Purchase #2	$196.56	5.851%	$208.0607	$208.06	$208.05	$208.10
Purchase #3	$55.40	11.871%	$61.9765	$61.98	$62.00	$62.00
Purchase #4	$200.40	10.427%	$221.2957	$221.30	$221.30	$221.30
Purchase #5	$88.92	13.335%	$100.7775	$100.78	$100.80	$100.80
Purchase #6	$235.35	8.838%	$256.1502	$256.15	$256.15	$256.20
Purchase #7	$160.44	13.184%	$181.5924	$181.59	$181.60	$181.60
7 purchase totals =	$952.56		$1,046.7840	$1,046.79	$1,046.85	$1,046.90