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	$115.64	3.303%	$119.4596	$119.46	$119.45	$119.50
Purchase #2	$36.35	10.352%	$40.113	$40.11	$40.10	$40.10
Purchase #3	$166.97	11.190%	$185.6539	$185.65	$185.65	$185.70
Purchase #4	$12.88	8.423%	$13.9649	$13.96	$13.95	$14.00
Purchase #5	$171.43	11.685%	$191.4616	$191.46	$191.45	$191.50
Purchase #6	$69.57	5.425%	$73.3442	$73.34	$73.35	$73.30
Purchase #7	$106.50	4.791%	$111.6024	$111.60	$111.60	$111.60
7 purchase totals =	$679.34		$735.5996	$735.58	$735.55	$735.70