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	$78.55	9.410%	$85.9416	$85.94	$85.95	$85.90
Purchase #2	$60.92	9.363%	$66.6239	$66.62	$66.60	$66.60
Purchase #3	$32.46	6.158%	$34.4589	$34.46	$34.45	$34.50
Purchase #4	$62.51	8.507%	$67.8277	$67.83	$67.85	$67.80
Purchase #5	$153.81	3.401%	$159.0411	$159.04	$159.05	$159.00
Purchase #6	$174.97	4.412%	$182.6897	$182.69	$182.70	$182.70
Purchase #7	$90.46	9.175%	$98.7597	$98.76	$98.75	$98.80
7 purchase totals =	$653.68		$695.3426	$695.34	$695.35	$695.30