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	$105.84	8.510%	$114.847	$114.85	$114.85	$114.80
Purchase #2	$72.78	8.319%	$78.8346	$78.83	$78.85	$78.80
Purchase #3	$85.63	12.174%	$96.0546	$96.05	$96.05	$96.10
Purchase #4	$225.73	10.341%	$249.0727	$249.07	$249.05	$249.10
Purchase #5	$160.38	3.162%	$165.4512	$165.45	$165.45	$165.50
Purchase #6	$226.29	3.256%	$233.658	$233.66	$233.65	$233.70
Purchase #7	$123.82	8.173%	$133.9398	$133.94	$133.95	$133.90
7 purchase totals =	$1,000.47		$1,071.8579	$1,071.85	$1,071.85	$1,071.90