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	$219.93	4.812%	$230.513	$230.51	$230.50	$230.50
Purchase #2	$90.76	10.342%	$100.1464	$100.15	$100.15	$100.10
Purchase #3	$136.59	12.792%	$154.0626	$154.06	$154.05	$154.10
Purchase #4	$216.88	11.826%	$242.5282	$242.53	$242.55	$242.50
Purchase #5	$227.45	11.490%	$253.584	$253.58	$253.60	$253.60
Purchase #6	$150.70	4.507%	$157.492	$157.49	$157.50	$157.50
Purchase #7	$46.60	5.814%	$49.3093	$49.31	$49.30	$49.30
7 purchase totals =	$1,088.91		$1,187.6355	$1,187.63	$1,187.65	$1,187.60