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	$119.56	7.136%	$128.0918	$128.09	$128.10	$128.10
Purchase #2	$230.31	7.248%	$247.0029	$247.00	$247.00	$247.00
Purchase #3	$6.89	6.130%	$7.3124	$7.31	$7.30	$7.30
Purchase #4	$215.39	5.451%	$227.1309	$227.13	$227.15	$227.10
Purchase #5	$192.76	6.811%	$205.8889	$205.89	$205.90	$205.90
Purchase #6	$106.36	4.552%	$111.2015	$111.20	$111.20	$111.20
Purchase #7	$169.71	12.491%	$190.9085	$190.91	$190.90	$190.90
7 purchase totals =	$1,040.98		$1,117.5369	$1,117.53	$1,117.55	$1,117.50