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	$213.61	10.367%	$235.7549	$235.75	$235.75	$235.80
Purchase #2	$126.34	13.544%	$143.4515	$143.45	$143.45	$143.50
Purchase #3	$27.45	3.424%	$28.3899	$28.39	$28.40	$28.40
Purchase #4	$128.50	10.771%	$142.3407	$142.34	$142.35	$142.30
Purchase #5	$99.95	5.635%	$105.5822	$105.58	$105.60	$105.60
Purchase #6	$62.27	6.125%	$66.084	$66.08	$66.10	$66.10
Purchase #7	$29.51	12.756%	$33.2743	$33.27	$33.25	$33.30
7 purchase totals =	$687.63		$754.8775	$754.86	$754.90	$755.00