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	$146.98	10.536%	$162.4658	$162.47	$162.45	$162.50
Purchase #2	$18.55	5.406%	$19.5528	$19.55	$19.55	$19.60
Purchase #3	$131.68	10.396%	$145.3695	$145.37	$145.35	$145.40
Purchase #4	$132.67	11.251%	$147.5967	$147.60	$147.60	$147.60
Purchase #5	$22.61	13.314%	$25.6203	$25.62	$25.60	$25.60
Purchase #6	$154.40	6.826%	$164.9393	$164.94	$164.95	$164.90
Purchase #7	$37.61	4.287%	$39.2223	$39.22	$39.20	$39.20
7 purchase totals =	$644.50		$704.7667	$704.77	$704.70	$704.80