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	$148.65	10.842%	$164.7666	$164.77	$164.75	$164.80
Purchase #2	$112.42	7.454%	$120.7998	$120.80	$120.80	$120.80
Purchase #3	$221.44	11.480%	$246.8613	$246.86	$246.85	$246.90
Purchase #4	$106.29	4.831%	$111.4249	$111.42	$111.40	$111.40
Purchase #5	$128.83	10.198%	$141.9681	$141.97	$141.95	$142.00
Purchase #6	$248.71	5.718%	$262.9312	$262.93	$262.95	$262.90
Purchase #7	$16.48	12.568%	$18.5512	$18.55	$18.55	$18.60
7 purchase totals =	$982.82		$1,067.3031	$1,067.30	$1,067.25	$1,067.40