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	$160.50	5.386%	$169.1445	$169.14	$169.15	$169.10
Purchase #2	$32.34	13.783%	$36.7974	$36.80	$36.80	$36.80
Purchase #3	$38.58	13.524%	$43.7976	$43.80	$43.80	$43.80
Purchase #4	$48.32	5.244%	$50.8539	$50.85	$50.85	$50.90
Purchase #5	$104.90	7.204%	$112.457	$112.46	$112.45	$112.50
Purchase #6	$226.72	8.429%	$245.8302	$245.83	$245.85	$245.80
Purchase #7	$60.79	6.464%	$64.7195	$64.72	$64.70	$64.70
7 purchase totals =	$672.15		$723.6001	$723.60	$723.60	$723.60