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	$148.60	5.426%	$156.663	$156.66	$156.65	$156.70
Purchase #2	$63.32	6.311%	$67.3161	$67.32	$67.30	$67.30
Purchase #3	$13.40	3.495%	$13.8683	$13.87	$13.85	$13.90
Purchase #4	$85.87	10.828%	$95.168	$95.17	$95.15	$95.20
Purchase #5	$147.82	4.494%	$154.463	$154.46	$154.45	$154.50
Purchase #6	$43.50	11.754%	$48.613	$48.61	$48.60	$48.60
Purchase #7	$245.44	4.103%	$255.5104	$255.51	$255.50	$255.50
7 purchase totals =	$747.95		$791.6018	$791.60	$791.50	$791.70