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	$12.57	11.800%	$14.0533	$14.05	$14.05	$14.10
Purchase #2	$200.76	13.543%	$227.9489	$227.95	$227.95	$227.90
Purchase #3	$9.48	8.294%	$10.2663	$10.27	$10.25	$10.30
Purchase #4	$105.61	5.525%	$111.445	$111.45	$111.45	$111.40
Purchase #5	$236.35	10.492%	$261.1478	$261.15	$261.15	$261.10
Purchase #6	$105.46	6.660%	$112.4836	$112.48	$112.50	$112.50
Purchase #7	$244.53	8.222%	$264.6353	$264.64	$264.65	$264.60
7 purchase totals =	$914.76		$1,001.9802	$1,001.99	$1,002.00	$1,001.90