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	$87.95	8.803%	$95.6922	$95.69	$95.70	$95.70
Purchase #2	$217.25	3.604%	$225.0797	$225.08	$225.10	$225.10
Purchase #3	$183.40	10.872%	$203.3392	$203.34	$203.35	$203.30
Purchase #4	$151.52	10.444%	$167.3447	$167.34	$167.35	$167.30
Purchase #5	$219.30	3.270%	$226.4711	$226.47	$226.45	$226.50
Purchase #6	$81.67	9.710%	$89.6002	$89.60	$89.60	$89.60
Purchase #7	$10.71	11.367%	$11.9274	$11.93	$11.95	$11.90
7 purchase totals =	$951.80		$1,019.4545	$1,019.45	$1,019.50	$1,019.40