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	$147.69	10.453%	$163.128	$163.13	$163.15	$163.10
Purchase #2	$215.38	4.870%	$225.869	$225.87	$225.85	$225.90
Purchase #3	$235.42	6.140%	$249.8748	$249.87	$249.85	$249.90
Purchase #4	$249.86	3.844%	$259.4646	$259.46	$259.45	$259.50
Purchase #5	$15.44	4.339%	$16.1099	$16.11	$16.10	$16.10
Purchase #6	$76.27	8.550%	$82.7911	$82.79	$82.80	$82.80
Purchase #7	$20.83	4.538%	$21.7753	$21.78	$21.80	$21.80
7 purchase totals =	$960.89		$1,019.0127	$1,019.01	$1,019.00	$1,019.10