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	$45.98	4.415%	$48.01	$48.01	$48.00	$48.00
Purchase #2	$194.87	7.642%	$209.762	$209.76	$209.75	$209.80
Purchase #3	$96.30	3.797%	$99.9565	$99.96	$99.95	$100.00
Purchase #4	$193.62	7.659%	$208.4494	$208.45	$208.45	$208.40
Purchase #5	$172.51	13.867%	$196.432	$196.43	$196.45	$196.40
Purchase #6	$20.86	6.172%	$22.1475	$22.15	$22.15	$22.10
Purchase #7	$155.63	11.547%	$173.6006	$173.60	$173.60	$173.60
7 purchase totals =	$879.77		$958.3580	$958.36	$958.35	$958.30