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	$195.98	8.833%	$213.2909	$213.29	$213.30	$213.30
Purchase #2	$105.49	5.501%	$111.293	$111.29	$111.30	$111.30
Purchase #3	$236.49	5.509%	$249.5182	$249.52	$249.50	$249.50
Purchase #4	$108.46	9.113%	$118.344	$118.34	$118.35	$118.30
Purchase #5	$140.73	4.504%	$147.0685	$147.07	$147.05	$147.10
Purchase #6	$106.93	3.160%	$110.309	$110.31	$110.30	$110.30
Purchase #7	$80.62	5.870%	$85.3524	$85.35	$85.35	$85.40
7 purchase totals =	$974.70		$1,035.1760	$1,035.17	$1,035.15	$1,035.20