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	$207.64	10.620%	$229.6914	$229.69	$229.70	$229.70
Purchase #2	$53.29	5.637%	$56.294	$56.29	$56.30	$56.30
Purchase #3	$131.86	13.323%	$149.4277	$149.43	$149.45	$149.40
Purchase #4	$194.70	10.770%	$215.6692	$215.67	$215.65	$215.70
Purchase #5	$100.77	13.314%	$114.1865	$114.19	$114.20	$114.20
Purchase #6	$168.76	13.630%	$191.762	$191.76	$191.75	$191.80
Purchase #7	$94.32	5.552%	$99.5566	$99.56	$99.55	$99.60
7 purchase totals =	$951.34		$1,056.5874	$1,056.59	$1,056.60	$1,056.70