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	$144.89	6.167%	$153.8254	$153.83	$153.85	$153.80
Purchase #2	$10.26	8.759%	$11.1587	$11.16	$11.15	$11.20
Purchase #3	$25.98	4.321%	$27.1026	$27.10	$27.10	$27.10
Purchase #4	$190.69	3.198%	$196.7883	$196.79	$196.80	$196.80
Purchase #5	$200.96	12.762%	$226.6065	$226.61	$226.60	$226.60
Purchase #6	$152.40	4.316%	$158.9776	$158.98	$159.00	$159.00
Purchase #7	$240.87	12.794%	$271.6869	$271.69	$271.70	$271.70
7 purchase totals =	$966.05		$1,046.1460	$1,046.16	$1,046.20	$1,046.20