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	$196.90	8.548%	$213.731	$213.73	$213.75	$213.70
Purchase #2	$67.62	9.305%	$73.912	$73.91	$73.90	$73.90
Purchase #3	$55.67	6.787%	$59.4483	$59.45	$59.45	$59.40
Purchase #4	$40.34	13.589%	$45.8218	$45.82	$45.80	$45.80
Purchase #5	$143.39	3.278%	$148.0903	$148.09	$148.10	$148.10
Purchase #6	$118.51	7.652%	$127.5784	$127.58	$127.60	$127.60
Purchase #7	$52.76	7.222%	$56.5703	$56.57	$56.55	$56.60
7 purchase totals =	$675.19		$725.1521	$725.15	$725.15	$725.10