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	$93.66	8.460%	$101.5836	$101.58	$101.60	$101.60
Purchase #2	$13.76	5.339%	$14.4946	$14.49	$14.50	$14.50
Purchase #3	$236.82	11.728%	$264.5942	$264.59	$264.60	$264.60
Purchase #4	$20.46	6.159%	$21.7201	$21.72	$21.70	$21.70
Purchase #5	$208.37	6.447%	$221.8036	$221.80	$221.80	$221.80
Purchase #6	$66.80	7.272%	$71.6577	$71.66	$71.65	$71.70
Purchase #7	$191.89	4.247%	$200.0396	$200.04	$200.05	$200.00
7 purchase totals =	$831.76		$895.8934	$895.88	$895.90	$895.90