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	$152.39	8.188%	$164.8677	$164.87	$164.85	$164.90
Purchase #2	$19.82	3.281%	$20.4703	$20.47	$20.45	$20.50
Purchase #3	$207.51	3.386%	$214.5363	$214.54	$214.55	$214.50
Purchase #4	$214.65	11.185%	$238.6586	$238.66	$238.65	$238.70
Purchase #5	$239.91	12.414%	$269.6924	$269.69	$269.70	$269.70
Purchase #6	$75.95	9.841%	$83.4242	$83.42	$83.40	$83.40
Purchase #7	$65.52	8.682%	$71.2084	$71.21	$71.20	$71.20
7 purchase totals =	$975.75		$1,062.8579	$1,062.86	$1,062.80	$1,062.90