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	$213.39	5.821%	$225.8114	$225.81	$225.80	$225.80
Purchase #2	$160.97	4.416%	$168.0784	$168.08	$168.10	$168.10
Purchase #3	$207.51	11.716%	$231.8219	$231.82	$231.80	$231.80
Purchase #4	$146.83	3.248%	$151.599	$151.60	$151.60	$151.60
Purchase #5	$148.91	7.783%	$160.4997	$160.50	$160.50	$160.50
Purchase #6	$210.79	5.362%	$222.0926	$222.09	$222.10	$222.10
Purchase #7	$84.29	12.846%	$95.1179	$95.12	$95.10	$95.10
7 purchase totals =	$1,172.69		$1,255.0209	$1,255.02	$1,255.00	$1,255.00