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	$57.45	8.650%	$62.4194	$62.42	$62.40	$62.40
Purchase #2	$213.34	9.359%	$233.3065	$233.31	$233.30	$233.30
Purchase #3	$202.87	8.322%	$219.7528	$219.75	$219.75	$219.80
Purchase #4	$125.66	8.123%	$135.8674	$135.87	$135.85	$135.90
Purchase #5	$138.55	5.586%	$146.2894	$146.29	$146.30	$146.30
Purchase #6	$205.67	10.511%	$227.288	$227.29	$227.30	$227.30
Purchase #7	$165.47	3.667%	$171.5378	$171.54	$171.55	$171.50
7 purchase totals =	$1,109.01		$1,196.4613	$1,196.47	$1,196.45	$1,196.50