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	$147.27	3.452%	$152.3538	$152.35	$152.35	$152.40
Purchase #2	$117.72	12.818%	$132.8093	$132.81	$132.80	$132.80
Purchase #3	$11.72	11.199%	$13.0325	$13.03	$13.05	$13.00
Purchase #4	$182.72	6.509%	$194.6132	$194.61	$194.60	$194.60
Purchase #5	$240.46	5.613%	$253.957	$253.96	$253.95	$254.00
Purchase #6	$216.86	10.858%	$240.4067	$240.41	$240.40	$240.40
Purchase #7	$35.31	11.226%	$39.2739	$39.27	$39.25	$39.30
7 purchase totals =	$952.06		$1,026.4464	$1,026.44	$1,026.40	$1,026.50