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	$165.25	5.762%	$174.7717	$174.77	$174.75	$174.80
Purchase #2	$36.95	8.468%	$40.0789	$40.08	$40.10	$40.10
Purchase #3	$180.30	11.301%	$200.6757	$200.68	$200.70	$200.70
Purchase #4	$116.60	13.342%	$132.1568	$132.16	$132.15	$132.20
Purchase #5	$161.73	3.427%	$167.2725	$167.27	$167.25	$167.30
Purchase #6	$176.75	7.196%	$189.4689	$189.47	$189.45	$189.50
Purchase #7	$137.64	11.407%	$153.3406	$153.34	$153.35	$153.30
7 purchase totals =	$975.22		$1,057.7651	$1,057.77	$1,057.75	$1,057.90