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	$69.71	9.769%	$76.52	$76.52	$76.50	$76.50
Purchase #2	$9.58	5.838%	$10.1393	$10.14	$10.15	$10.10
Purchase #3	$52.37	5.303%	$55.1472	$55.15	$55.15	$55.10
Purchase #4	$18.85	3.245%	$19.4617	$19.46	$19.45	$19.50
Purchase #5	$179.83	9.374%	$196.6873	$196.69	$196.70	$196.70
Purchase #6	$207.67	4.528%	$217.0733	$217.07	$217.05	$217.10
Purchase #7	$146.83	13.755%	$167.0265	$167.03	$167.05	$167.00
7 purchase totals =	$684.84		$742.0553	$742.06	$742.05	$742.00