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	$216.70	10.552%	$239.5662	$239.57	$239.55	$239.60
Purchase #2	$219.35	13.709%	$249.4207	$249.42	$249.40	$249.40
Purchase #3	$184.69	3.319%	$190.8199	$190.82	$190.80	$190.80
Purchase #4	$18.54	3.327%	$19.1568	$19.16	$19.15	$19.20
Purchase #5	$143.90	10.102%	$158.4368	$158.44	$158.45	$158.40
Purchase #6	$92.68	13.562%	$105.2493	$105.25	$105.25	$105.20
Purchase #7	$213.46	4.452%	$222.9632	$222.96	$222.95	$223.00
7 purchase totals =	$1,089.32		$1,185.6129	$1,185.62	$1,185.55	$1,185.60