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	$119.60	5.212%	$125.8336	$125.83	$125.85	$125.80
Purchase #2	$153.80	11.683%	$171.7685	$171.77	$171.75	$171.80
Purchase #3	$127.79	10.841%	$141.6437	$141.64	$141.65	$141.60
Purchase #4	$40.74	3.434%	$42.139	$42.14	$42.15	$42.10
Purchase #5	$117.65	13.290%	$133.2857	$133.29	$133.30	$133.30
Purchase #6	$91.82	6.741%	$98.0096	$98.01	$98.00	$98.00
Purchase #7	$12.47	10.417%	$13.769	$13.77	$13.75	$13.80
7 purchase totals =	$663.87		$726.4491	$726.45	$726.45	$726.40