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	$185.93	5.670%	$196.4722	$196.47	$196.45	$196.50
Purchase #2	$218.92	5.238%	$230.387	$230.39	$230.40	$230.40
Purchase #3	$18.25	7.492%	$19.6173	$19.62	$19.60	$19.60
Purchase #4	$212.51	11.755%	$237.4906	$237.49	$237.50	$237.50
Purchase #5	$79.37	12.854%	$89.5722	$89.57	$89.55	$89.60
Purchase #6	$230.95	3.263%	$238.4859	$238.49	$238.50	$238.50
Purchase #7	$140.25	4.133%	$146.0465	$146.05	$146.05	$146.00
7 purchase totals =	$1,086.18		$1,158.0717	$1,158.08	$1,158.05	$1,158.10