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	$83.59	13.179%	$94.6063	$94.61	$94.60	$94.60
Purchase #2	$18.89	7.291%	$20.2673	$20.27	$20.25	$20.30
Purchase #3	$62.37	11.565%	$69.5831	$69.58	$69.60	$69.60
Purchase #4	$53.45	3.297%	$55.2122	$55.21	$55.20	$55.20
Purchase #5	$190.51	13.151%	$215.564	$215.56	$215.55	$215.60
Purchase #6	$63.27	3.527%	$65.5015	$65.50	$65.50	$65.50
Purchase #7	$23.46	4.845%	$24.5966	$24.60	$24.60	$24.60
7 purchase totals =	$495.54		$545.3310	$545.33	$545.30	$545.40