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	$197.40	10.713%	$218.5475	$218.55	$218.55	$218.50
Purchase #2	$203.60	3.370%	$210.4613	$210.46	$210.45	$210.50
Purchase #3	$57.27	4.244%	$59.7005	$59.70	$59.70	$59.70
Purchase #4	$87.70	5.821%	$92.805	$92.81	$92.80	$92.80
Purchase #5	$34.84	8.868%	$37.9296	$37.93	$37.95	$37.90
Purchase #6	$19.51	8.747%	$21.2165	$21.22	$21.20	$21.20
Purchase #7	$61.25	6.666%	$65.3329	$65.33	$65.35	$65.30
7 purchase totals =	$661.57		$705.9933	$706.00	$706.00	$705.90