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	$90.73	6.188%	$96.3444	$96.34	$96.35	$96.30
Purchase #2	$14.58	7.422%	$15.6621	$15.66	$15.65	$15.70
Purchase #3	$33.95	11.455%	$37.839	$37.84	$37.85	$37.80
Purchase #4	$177.85	5.815%	$188.192	$188.19	$188.20	$188.20
Purchase #5	$12.46	11.759%	$13.9252	$13.93	$13.95	$13.90
Purchase #6	$41.89	9.417%	$45.8348	$45.83	$45.85	$45.80
Purchase #7	$245.64	4.207%	$255.9741	$255.97	$255.95	$256.00
7 purchase totals =	$617.10		$653.7716	$653.76	$653.80	$653.70