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	$108.73	13.393%	$123.2922	$123.29	$123.30	$123.30
Purchase #2	$12.37	3.853%	$12.8466	$12.85	$12.85	$12.80
Purchase #3	$162.84	4.622%	$170.3665	$170.37	$170.35	$170.40
Purchase #4	$199.93	11.443%	$222.808	$222.81	$222.80	$222.80
Purchase #5	$69.94	4.306%	$72.9516	$72.95	$72.95	$73.00
Purchase #6	$247.57	7.611%	$266.4126	$266.41	$266.40	$266.40
Purchase #7	$161.36	10.454%	$178.2286	$178.23	$178.25	$178.20
7 purchase totals =	$962.74		$1,046.9061	$1,046.91	$1,046.90	$1,046.90