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	$91.82	11.536%	$102.4124	$102.41	$102.40	$102.40
Purchase #2	$94.87	5.376%	$99.9702	$99.97	$99.95	$100.00
Purchase #3	$249.55	12.854%	$281.6272	$281.63	$281.65	$281.60
Purchase #4	$223.82	6.158%	$237.6028	$237.60	$237.60	$237.60
Purchase #5	$59.49	3.472%	$61.5555	$61.56	$61.55	$61.60
Purchase #6	$77.83	12.129%	$87.27	$87.27	$87.25	$87.30
Purchase #7	$225.59	8.388%	$244.5125	$244.51	$244.50	$244.50
7 purchase totals =	$1,022.97		$1,114.9506	$1,114.95	$1,114.90	$1,115.00