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	$161.27	11.247%	$179.408	$179.41	$179.40	$179.40
Purchase #2	$196.29	7.729%	$211.4613	$211.46	$211.45	$211.50
Purchase #3	$230.60	11.224%	$256.4825	$256.48	$256.50	$256.50
Purchase #4	$45.70	6.666%	$48.7464	$48.75	$48.75	$48.70
Purchase #5	$242.80	9.462%	$265.7737	$265.77	$265.75	$265.80
Purchase #6	$220.31	11.472%	$245.584	$245.58	$245.60	$245.60
Purchase #7	$236.93	13.745%	$269.496	$269.50	$269.50	$269.50
7 purchase totals =	$1,333.90		$1,476.9519	$1,476.95	$1,476.95	$1,477.00