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	$117.37	11.349%	$130.6903	$130.69	$130.70	$130.70
Purchase #2	$194.89	8.525%	$211.5044	$211.50	$211.50	$211.50
Purchase #3	$38.66	13.219%	$43.7705	$43.77	$43.75	$43.80
Purchase #4	$13.26	10.791%	$14.6909	$14.69	$14.70	$14.70
Purchase #5	$48.89	5.519%	$51.5882	$51.59	$51.60	$51.60
Purchase #6	$136.32	7.196%	$146.1296	$146.13	$146.15	$146.10
Purchase #7	$138.43	4.447%	$144.586	$144.59	$144.60	$144.60
7 purchase totals =	$687.82		$742.9599	$742.96	$743.00	$743.00