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	$195.88	13.562%	$222.4452	$222.45	$222.45	$222.40
Purchase #2	$243.60	11.370%	$271.2973	$271.30	$271.30	$271.30
Purchase #3	$77.68	5.677%	$82.0899	$82.09	$82.10	$82.10
Purchase #4	$39.64	3.537%	$41.0421	$41.04	$41.05	$41.00
Purchase #5	$196.59	6.429%	$209.2288	$209.23	$209.25	$209.20
Purchase #6	$187.97	6.718%	$200.5978	$200.60	$200.60	$200.60
Purchase #7	$177.76	11.824%	$198.7783	$198.78	$198.80	$198.80
7 purchase totals =	$1,119.12		$1,225.4794	$1,225.49	$1,225.55	$1,225.40