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	$200.59	11.485%	$223.6278	$223.63	$223.65	$223.60
Purchase #2	$238.25	11.151%	$264.8173	$264.82	$264.80	$264.80
Purchase #3	$12.71	3.456%	$13.1493	$13.15	$13.15	$13.10
Purchase #4	$23.45	5.314%	$24.6961	$24.70	$24.70	$24.70
Purchase #5	$220.37	12.337%	$247.557	$247.56	$247.55	$247.60
Purchase #6	$239.72	6.778%	$255.9682	$255.97	$255.95	$256.00
Purchase #7	$86.56	4.613%	$90.553	$90.55	$90.55	$90.60
7 purchase totals =	$1,021.65		$1,120.3687	$1,120.38	$1,120.35	$1,120.40