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	$86.61	9.637%	$94.9566	$94.96	$94.95	$95.00
Purchase #2	$29.94	8.534%	$32.4951	$32.50	$32.50	$32.50
Purchase #3	$158.91	4.625%	$166.2596	$166.26	$166.25	$166.30
Purchase #4	$78.39	5.392%	$82.6168	$82.62	$82.60	$82.60
Purchase #5	$109.71	8.692%	$119.246	$119.25	$119.25	$119.20
Purchase #6	$80.97	8.343%	$87.7253	$87.73	$87.75	$87.70
Purchase #7	$84.29	6.214%	$89.5278	$89.53	$89.55	$89.50
7 purchase totals =	$628.82		$672.8272	$672.85	$672.85	$672.80