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	$195.28	9.868%	$214.5502	$214.55	$214.55	$214.60
Purchase #2	$54.79	11.493%	$61.087	$61.09	$61.10	$61.10
Purchase #3	$41.50	11.198%	$46.1472	$46.15	$46.15	$46.10
Purchase #4	$72.51	7.802%	$78.1672	$78.17	$78.15	$78.20
Purchase #5	$144.74	3.647%	$150.0187	$150.02	$150.00	$150.00
Purchase #6	$117.39	7.479%	$126.1696	$126.17	$126.15	$126.20
Purchase #7	$249.64	12.632%	$281.1745	$281.17	$281.15	$281.20
7 purchase totals =	$875.85		$957.3144	$957.32	$957.25	$957.40