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	$176.29	9.741%	$193.4624	$193.46	$193.45	$193.50
Purchase #2	$113.59	4.165%	$118.321	$118.32	$118.30	$118.30
Purchase #3	$99.28	9.182%	$108.3959	$108.40	$108.40	$108.40
Purchase #4	$127.26	13.759%	$144.7697	$144.77	$144.75	$144.80
Purchase #5	$227.42	11.389%	$253.3209	$253.32	$253.30	$253.30
Purchase #6	$200.98	7.212%	$215.4747	$215.47	$215.45	$215.50
Purchase #7	$118.34	11.773%	$132.2722	$132.27	$132.25	$132.30
7 purchase totals =	$1,063.16		$1,166.0168	$1,166.01	$1,165.90	$1,166.10