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	$152.62	13.185%	$172.7429	$172.74	$172.75	$172.70
Purchase #2	$223.90	5.215%	$235.5764	$235.58	$235.60	$235.60
Purchase #3	$67.81	9.348%	$74.1489	$74.15	$74.15	$74.10
Purchase #4	$223.83	13.231%	$253.4449	$253.44	$253.45	$253.40
Purchase #5	$12.55	6.659%	$13.3857	$13.39	$13.40	$13.40
Purchase #6	$150.38	10.604%	$166.3263	$166.33	$166.35	$166.30
Purchase #7	$125.63	4.330%	$131.0698	$131.07	$131.05	$131.10
7 purchase totals =	$956.72		$1,046.6949	$1,046.70	$1,046.75	$1,046.60