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	$56.44	11.195%	$62.7585	$62.76	$62.75	$62.80
Purchase #2	$49.79	5.351%	$52.4543	$52.45	$52.45	$52.50
Purchase #3	$144.59	6.797%	$154.4178	$154.42	$154.40	$154.40
Purchase #4	$9.77	5.475%	$10.3049	$10.30	$10.30	$10.30
Purchase #5	$122.48	7.421%	$131.5692	$131.57	$131.55	$131.60
Purchase #6	$153.90	7.593%	$165.5856	$165.59	$165.60	$165.60
Purchase #7	$74.91	7.395%	$80.4496	$80.45	$80.45	$80.40
7 purchase totals =	$611.88		$657.5399	$657.54	$657.50	$657.60