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	$197.88	10.456%	$218.5703	$218.57	$218.55	$218.60
Purchase #2	$90.83	4.846%	$95.2316	$95.23	$95.25	$95.20
Purchase #3	$154.81	7.687%	$166.7102	$166.71	$166.70	$166.70
Purchase #4	$70.45	3.311%	$72.7826	$72.78	$72.80	$72.80
Purchase #5	$76.72	11.762%	$85.7438	$85.74	$85.75	$85.70
Purchase #6	$19.77	12.289%	$22.1995	$22.20	$22.20	$22.20
Purchase #7	$19.66	4.626%	$20.5695	$20.57	$20.55	$20.60
7 purchase totals =	$630.12		$681.8075	$681.80	$681.80	$681.80