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	$132.72	13.726%	$150.9371	$150.94	$150.95	$150.90
Purchase #2	$118.34	4.869%	$124.102	$124.10	$124.10	$124.10
Purchase #3	$12.58	3.612%	$13.0344	$13.03	$13.05	$13.00
Purchase #4	$64.87	7.645%	$69.8293	$69.83	$69.85	$69.80
Purchase #5	$113.79	12.246%	$127.7247	$127.72	$127.70	$127.70
Purchase #6	$184.82	6.301%	$196.4655	$196.47	$196.45	$196.50
Purchase #7	$66.75	10.272%	$73.6066	$73.61	$73.60	$73.60
7 purchase totals =	$693.87		$755.6996	$755.70	$755.70	$755.60