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	$49.47	7.470%	$53.1654	$53.17	$53.15	$53.20
Purchase #2	$146.48	10.382%	$161.6876	$161.69	$161.70	$161.70
Purchase #3	$94.78	10.703%	$104.9243	$104.92	$104.90	$104.90
Purchase #4	$239.91	6.649%	$255.8616	$255.86	$255.85	$255.90
Purchase #5	$20.41	7.213%	$21.8822	$21.88	$21.90	$21.90
Purchase #6	$159.76	10.302%	$176.2185	$176.22	$176.20	$176.20
Purchase #7	$247.43	10.326%	$272.9796	$272.98	$273.00	$273.00
7 purchase totals =	$958.24		$1,046.7192	$1,046.72	$1,046.70	$1,046.80