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	$143.37	11.191%	$159.4145	$159.41	$159.40	$159.40
Purchase #2	$138.94	5.152%	$146.0982	$146.10	$146.10	$146.10
Purchase #3	$67.78	4.299%	$70.6939	$70.69	$70.70	$70.70
Purchase #4	$215.55	13.853%	$245.4101	$245.41	$245.40	$245.40
Purchase #5	$109.71	4.141%	$114.2531	$114.25	$114.25	$114.30
Purchase #6	$217.66	9.557%	$238.4618	$238.46	$238.45	$238.50
Purchase #7	$46.34	10.429%	$51.1728	$51.17	$51.15	$51.20
7 purchase totals =	$939.35		$1,025.5044	$1,025.49	$1,025.45	$1,025.60