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	$57.34	6.587%	$61.117	$61.12	$61.10	$61.10
Purchase #2	$46.97	5.678%	$49.637	$49.64	$49.65	$49.60
Purchase #3	$242.40	5.482%	$255.6884	$255.69	$255.70	$255.70
Purchase #4	$196.85	13.668%	$223.7555	$223.76	$223.75	$223.80
Purchase #5	$180.86	7.268%	$194.0049	$194.00	$194.00	$194.00
Purchase #6	$46.39	10.864%	$51.4298	$51.43	$51.45	$51.40
Purchase #7	$234.33	12.664%	$264.0056	$264.01	$264.00	$264.00
7 purchase totals =	$1,005.14		$1,099.6382	$1,099.65	$1,099.65	$1,099.60