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	$214.77	13.463%	$243.6845	$243.68	$243.70	$243.70
Purchase #2	$215.57	3.870%	$223.9126	$223.91	$223.90	$223.90
Purchase #3	$112.38	13.327%	$127.3569	$127.36	$127.35	$127.40
Purchase #4	$144.41	6.492%	$153.7851	$153.79	$153.80	$153.80
Purchase #5	$106.99	4.581%	$111.8912	$111.89	$111.90	$111.90
Purchase #6	$91.36	12.813%	$103.066	$103.07	$103.05	$103.10
Purchase #7	$77.70	10.298%	$85.7015	$85.70	$85.70	$85.70
7 purchase totals =	$963.18		$1,049.3978	$1,049.40	$1,049.40	$1,049.50