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	$101.80	9.595%	$111.5677	$111.57	$111.55	$111.60
Purchase #2	$207.43	9.460%	$227.0529	$227.05	$227.05	$227.10
Purchase #3	$191.68	4.279%	$199.882	$199.88	$199.90	$199.90
Purchase #4	$130.99	7.463%	$140.7658	$140.77	$140.75	$140.80
Purchase #5	$103.42	9.196%	$112.9305	$112.93	$112.95	$112.90
Purchase #6	$67.54	12.665%	$76.0939	$76.09	$76.10	$76.10
Purchase #7	$199.71	8.502%	$216.6893	$216.69	$216.70	$216.70
7 purchase totals =	$1,002.57		$1,084.9821	$1,084.98	$1,085.00	$1,085.10