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	$116.99	5.684%	$123.6397	$123.64	$123.65	$123.60
Purchase #2	$184.85	3.267%	$190.889	$190.89	$190.90	$190.90
Purchase #3	$209.76	6.256%	$222.8826	$222.88	$222.90	$222.90
Purchase #4	$139.91	12.632%	$157.5834	$157.58	$157.60	$157.60
Purchase #5	$157.93	5.103%	$165.9892	$165.99	$166.00	$166.00
Purchase #6	$22.41	3.273%	$23.1435	$23.14	$23.15	$23.10
Purchase #7	$43.44	12.600%	$48.9134	$48.91	$48.90	$48.90
7 purchase totals =	$875.29		$933.0408	$933.03	$933.10	$933.00