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	$210.95	6.677%	$225.0351	$225.04	$225.05	$225.00
Purchase #2	$67.53	7.477%	$72.5792	$72.58	$72.60	$72.60
Purchase #3	$225.47	8.304%	$244.193	$244.19	$244.20	$244.20
Purchase #4	$79.38	7.794%	$85.5669	$85.57	$85.55	$85.60
Purchase #5	$69.89	4.166%	$72.8016	$72.80	$72.80	$72.80
Purchase #6	$118.39	8.574%	$128.5408	$128.54	$128.55	$128.50
Purchase #7	$110.50	6.602%	$117.7952	$117.80	$117.80	$117.80
7 purchase totals =	$882.11		$946.5118	$946.52	$946.55	$946.50