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	$242.97	6.164%	$257.9467	$257.95	$257.95	$257.90
Purchase #2	$53.61	3.823%	$55.6595	$55.66	$55.65	$55.70
Purchase #3	$70.75	8.157%	$76.5211	$76.52	$76.50	$76.50
Purchase #4	$72.36	13.552%	$82.1662	$82.17	$82.15	$82.20
Purchase #5	$105.69	5.456%	$111.4564	$111.46	$111.45	$111.50
Purchase #6	$186.63	11.245%	$207.6165	$207.62	$207.60	$207.60
Purchase #7	$246.33	10.384%	$271.9089	$271.91	$271.90	$271.90
7 purchase totals =	$978.34		$1,063.2753	$1,063.29	$1,063.20	$1,063.30