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	$85.81	11.506%	$95.6833	$95.68	$95.70	$95.70
Purchase #2	$213.38	4.814%	$223.6521	$223.65	$223.65	$223.70
Purchase #3	$62.62	6.219%	$66.5143	$66.51	$66.50	$66.50
Purchase #4	$114.66	8.271%	$124.1435	$124.14	$124.15	$124.10
Purchase #5	$89.85	10.298%	$99.1028	$99.10	$99.10	$99.10
Purchase #6	$250.66	6.347%	$266.5694	$266.57	$266.55	$266.60
Purchase #7	$63.36	13.858%	$72.1404	$72.14	$72.15	$72.10
7 purchase totals =	$880.34		$947.8058	$947.79	$947.80	$947.80