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	$125.34	5.348%	$132.0432	$132.04	$132.05	$132.00
Purchase #2	$60.64	11.476%	$67.599	$67.60	$67.60	$67.60
Purchase #3	$109.50	12.720%	$123.4284	$123.43	$123.45	$123.40
Purchase #4	$244.74	6.366%	$260.3201	$260.32	$260.30	$260.30
Purchase #5	$24.47	8.235%	$26.4851	$26.49	$26.50	$26.50
Purchase #6	$97.45	8.656%	$105.8853	$105.89	$105.90	$105.90
Purchase #7	$64.32	5.264%	$67.7058	$67.71	$67.70	$67.70
7 purchase totals =	$726.46		$783.4669	$783.48	$783.50	$783.40