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	$89.53	7.290%	$96.0567	$96.06	$96.05	$96.10
Purchase #2	$102.65	11.219%	$114.1663	$114.17	$114.15	$114.20
Purchase #3	$244.41	4.472%	$255.34	$255.34	$255.35	$255.30
Purchase #4	$44.61	4.715%	$46.7134	$46.71	$46.70	$46.70
Purchase #5	$247.93	4.771%	$259.7587	$259.76	$259.75	$259.80
Purchase #6	$37.93	12.584%	$42.7031	$42.70	$42.70	$42.70
Purchase #7	$143.32	3.284%	$148.0266	$148.03	$148.05	$148.00
7 purchase totals =	$910.38		$962.7648	$962.77	$962.75	$962.80