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	$198.98	8.604%	$216.1002	$216.10	$216.10	$216.10
Purchase #2	$118.47	4.138%	$123.3723	$123.37	$123.35	$123.40
Purchase #3	$43.67	3.372%	$45.1426	$45.14	$45.15	$45.10
Purchase #4	$47.48	8.238%	$51.3914	$51.39	$51.40	$51.40
Purchase #5	$223.90	5.281%	$235.7242	$235.72	$235.70	$235.70
Purchase #6	$240.65	6.512%	$256.3211	$256.32	$256.30	$256.30
Purchase #7	$77.89	9.869%	$85.577	$85.58	$85.60	$85.60
7 purchase totals =	$951.04		$1,013.6288	$1,013.62	$1,013.60	$1,013.60