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	$168.71	3.182%	$174.0784	$174.08	$174.10	$174.10
Purchase #2	$151.48	11.309%	$168.6109	$168.61	$168.60	$168.60
Purchase #3	$100.97	4.856%	$105.8731	$105.87	$105.85	$105.90
Purchase #4	$204.50	12.318%	$229.6903	$229.69	$229.70	$229.70
Purchase #5	$210.84	3.148%	$217.4772	$217.48	$217.50	$217.50
Purchase #6	$106.47	7.530%	$114.4872	$114.49	$114.50	$114.50
Purchase #7	$103.57	12.191%	$116.1962	$116.20	$116.20	$116.20
7 purchase totals =	$1,046.54		$1,126.4133	$1,126.42	$1,126.45	$1,126.50