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	$59.88	3.481%	$61.9644	$61.96	$61.95	$62.00
Purchase #2	$116.98	9.228%	$127.7749	$127.77	$127.75	$127.80
Purchase #3	$83.28	10.343%	$91.8937	$91.89	$91.90	$91.90
Purchase #4	$155.65	3.692%	$161.3966	$161.40	$161.40	$161.40
Purchase #5	$215.86	4.440%	$225.4442	$225.44	$225.45	$225.40
Purchase #6	$40.87	11.250%	$45.4679	$45.47	$45.45	$45.50
Purchase #7	$204.26	6.475%	$217.4858	$217.49	$217.50	$217.50
7 purchase totals =	$876.78		$931.4275	$931.42	$931.40	$931.50