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	$245.59	8.144%	$265.5908	$265.59	$265.60	$265.60
Purchase #2	$10.42	4.506%	$10.8895	$10.89	$10.90	$10.90
Purchase #3	$96.67	4.162%	$100.6934	$100.69	$100.70	$100.70
Purchase #4	$134.79	12.837%	$152.093	$152.09	$152.10	$152.10
Purchase #5	$35.34	12.496%	$39.7561	$39.76	$39.75	$39.80
Purchase #6	$129.95	3.107%	$133.9875	$133.99	$134.00	$134.00
Purchase #7	$215.83	13.732%	$245.4678	$245.47	$245.45	$245.50
7 purchase totals =	$868.59		$948.4781	$948.48	$948.50	$948.60