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	$56.87	8.465%	$61.684	$61.68	$61.70	$61.70
Purchase #2	$12.46	6.509%	$13.271	$13.27	$13.25	$13.30
Purchase #3	$42.89	6.104%	$45.508	$45.51	$45.50	$45.50
Purchase #4	$96.80	8.864%	$105.3804	$105.38	$105.40	$105.40
Purchase #5	$36.57	11.112%	$40.6337	$40.63	$40.65	$40.60
Purchase #6	$59.51	4.250%	$62.0392	$62.04	$62.05	$62.00
Purchase #7	$245.59	12.174%	$275.4881	$275.49	$275.50	$275.50
7 purchase totals =	$550.69		$604.0044	$604.00	$604.05	$604.00