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	$194.49	9.566%	$213.0949	$213.09	$213.10	$213.10
Purchase #2	$53.53	10.716%	$59.2663	$59.27	$59.25	$59.30
Purchase #3	$45.61	13.479%	$51.7578	$51.76	$51.75	$51.80
Purchase #4	$211.68	10.169%	$233.2057	$233.21	$233.20	$233.20
Purchase #5	$178.59	9.281%	$195.1649	$195.16	$195.15	$195.20
Purchase #6	$120.33	13.466%	$136.5336	$136.53	$136.55	$136.50
Purchase #7	$139.42	13.770%	$158.6181	$158.62	$158.60	$158.60
7 purchase totals =	$943.65		$1,047.6413	$1,047.64	$1,047.60	$1,047.70