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	$97.91	11.218%	$108.8935	$108.89	$108.90	$108.90
Purchase #2	$189.57	3.120%	$195.4846	$195.48	$195.50	$195.50
Purchase #3	$10.62	7.435%	$11.4096	$11.41	$11.40	$11.40
Purchase #4	$37.67	3.776%	$39.0924	$39.09	$39.10	$39.10
Purchase #5	$109.93	3.801%	$114.1084	$114.11	$114.10	$114.10
Purchase #6	$98.89	5.624%	$104.4516	$104.45	$104.45	$104.50
Purchase #7	$116.88	9.260%	$127.7031	$127.70	$127.70	$127.70
7 purchase totals =	$661.47		$701.1432	$701.13	$701.15	$701.20