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	$207.57	3.132%	$214.0711	$214.07	$214.05	$214.10
Purchase #2	$92.70	11.859%	$103.6933	$103.69	$103.70	$103.70
Purchase #3	$168.73	4.466%	$176.2655	$176.27	$176.25	$176.30
Purchase #4	$10.31	8.486%	$11.1849	$11.18	$11.20	$11.20
Purchase #5	$190.28	3.339%	$196.6334	$196.63	$196.65	$196.60
Purchase #6	$136.31	11.138%	$151.4922	$151.49	$151.50	$151.50
Purchase #7	$171.34	5.348%	$180.5033	$180.50	$180.50	$180.50
7 purchase totals =	$977.24		$1,033.8437	$1,033.83	$1,033.85	$1,033.90