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	$150.98	4.735%	$158.1289	$158.13	$158.15	$158.10
Purchase #2	$196.70	13.124%	$222.5149	$222.51	$222.50	$222.50
Purchase #3	$23.86	3.612%	$24.7218	$24.72	$24.70	$24.70
Purchase #4	$220.27	13.102%	$249.1298	$249.13	$249.15	$249.10
Purchase #5	$53.85	10.397%	$59.4488	$59.45	$59.45	$59.40
Purchase #6	$142.77	8.746%	$155.2567	$155.26	$155.25	$155.30
Purchase #7	$172.44	12.677%	$194.3002	$194.30	$194.30	$194.30
7 purchase totals =	$960.87		$1,063.5011	$1,063.50	$1,063.50	$1,063.40