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	$114.50	11.832%	$128.0476	$128.05	$128.05	$128.00
Purchase #2	$10.45	7.730%	$11.2578	$11.26	$11.25	$11.30
Purchase #3	$101.60	10.188%	$111.951	$111.95	$111.95	$112.00
Purchase #4	$55.41	3.581%	$57.3942	$57.39	$57.40	$57.40
Purchase #5	$10.59	3.571%	$10.9682	$10.97	$10.95	$11.00
Purchase #6	$140.46	5.213%	$147.7822	$147.78	$147.80	$147.80
Purchase #7	$137.56	11.742%	$153.7123	$153.71	$153.70	$153.70
7 purchase totals =	$570.57		$621.1133	$621.11	$621.10	$621.20