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	$83.92	10.397%	$92.6452	$92.65	$92.65	$92.60
Purchase #2	$27.93	13.446%	$31.6855	$31.69	$31.70	$31.70
Purchase #3	$78.62	10.618%	$86.9679	$86.97	$86.95	$87.00
Purchase #4	$67.85	3.376%	$70.1406	$70.14	$70.15	$70.10
Purchase #5	$122.52	5.128%	$128.8028	$128.80	$128.80	$128.80
Purchase #6	$70.60	11.343%	$78.6082	$78.61	$78.60	$78.60
Purchase #7	$231.78	5.211%	$243.8581	$243.86	$243.85	$243.90
7 purchase totals =	$683.22		$732.7083	$732.72	$732.70	$732.70