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	$75.33	13.840%	$85.7557	$85.76	$85.75	$85.80
Purchase #2	$88.91	10.455%	$98.2055	$98.21	$98.20	$98.20
Purchase #3	$98.25	4.188%	$102.3647	$102.36	$102.35	$102.40
Purchase #4	$237.81	10.503%	$262.7872	$262.79	$262.80	$262.80
Purchase #5	$56.85	10.215%	$62.6572	$62.66	$62.65	$62.70
Purchase #6	$154.47	12.211%	$173.3323	$173.33	$173.35	$173.30
Purchase #7	$215.49	7.486%	$231.6216	$231.62	$231.60	$231.60
7 purchase totals =	$927.11		$1,016.7242	$1,016.73	$1,016.70	$1,016.80