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	$193.92	9.656%	$212.6449	$212.64	$212.65	$212.60
Purchase #2	$180.95	10.752%	$200.4057	$200.41	$200.40	$200.40
Purchase #3	$11.86	10.772%	$13.1376	$13.14	$13.15	$13.10
Purchase #4	$45.54	3.508%	$47.1375	$47.14	$47.15	$47.10
Purchase #5	$235.64	8.253%	$255.0874	$255.09	$255.10	$255.10
Purchase #6	$105.90	5.521%	$111.7467	$111.75	$111.75	$111.70
Purchase #7	$151.52	10.736%	$167.7872	$167.79	$167.80	$167.80
7 purchase totals =	$925.33		$1,007.9470	$1,007.96	$1,008.00	$1,007.80