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	$202.54	4.401%	$211.4538	$211.45	$211.45	$211.50
Purchase #2	$9.71	7.709%	$10.4585	$10.46	$10.45	$10.50
Purchase #3	$41.72	9.433%	$45.6554	$45.66	$45.65	$45.70
Purchase #4	$85.38	11.598%	$95.2824	$95.28	$95.30	$95.30
Purchase #5	$78.93	8.599%	$85.7172	$85.72	$85.70	$85.70
Purchase #6	$153.31	13.139%	$173.4534	$173.45	$173.45	$173.50
Purchase #7	$213.33	13.720%	$242.5989	$242.60	$242.60	$242.60
7 purchase totals =	$784.92		$864.6196	$864.62	$864.60	$864.80