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	$164.72	4.195%	$171.63	$171.63	$171.65	$171.60
Purchase #2	$58.52	3.318%	$60.4617	$60.46	$60.45	$60.50
Purchase #3	$141.45	7.423%	$151.9498	$151.95	$151.95	$151.90
Purchase #4	$111.32	6.157%	$118.174	$118.17	$118.15	$118.20
Purchase #5	$111.53	6.136%	$118.3735	$118.37	$118.35	$118.40
Purchase #6	$56.84	7.393%	$61.0422	$61.04	$61.05	$61.00
Purchase #7	$43.31	9.693%	$47.508	$47.51	$47.50	$47.50
7 purchase totals =	$687.69		$729.1392	$729.13	$729.10	$729.10