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	$151.46	11.643%	$169.0945	$169.09	$169.10	$169.10
Purchase #2	$38.41	10.777%	$42.5494	$42.55	$42.55	$42.50
Purchase #3	$74.79	12.136%	$83.8665	$83.87	$83.85	$83.90
Purchase #4	$40.63	11.590%	$45.339	$45.34	$45.35	$45.30
Purchase #5	$207.76	5.119%	$218.3952	$218.40	$218.40	$218.40
Purchase #6	$214.52	13.528%	$243.5403	$243.54	$243.55	$243.50
Purchase #7	$207.58	3.530%	$214.9076	$214.91	$214.90	$214.90
7 purchase totals =	$935.15		$1,017.6925	$1,017.70	$1,017.70	$1,017.60