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	$98.43	7.201%	$105.5179	$105.52	$105.50	$105.50
Purchase #2	$99.36	6.783%	$106.0996	$106.10	$106.10	$106.10
Purchase #3	$168.45	5.704%	$178.0584	$178.06	$178.05	$178.10
Purchase #4	$206.86	7.476%	$222.3249	$222.32	$222.30	$222.30
Purchase #5	$99.87	11.578%	$111.4329	$111.43	$111.45	$111.40
Purchase #6	$138.65	7.412%	$148.9267	$148.93	$148.95	$148.90
Purchase #7	$161.48	7.577%	$173.7153	$173.72	$173.70	$173.70
7 purchase totals =	$973.10		$1,046.0757	$1,046.08	$1,046.05	$1,046.00