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	$85.59	9.788%	$93.9675	$93.97	$93.95	$94.00
Purchase #2	$212.52	4.749%	$222.6126	$222.61	$222.60	$222.60
Purchase #3	$189.84	10.549%	$209.8662	$209.87	$209.85	$209.90
Purchase #4	$242.51	12.638%	$273.1584	$273.16	$273.15	$273.20
Purchase #5	$115.84	13.831%	$131.8618	$131.86	$131.85	$131.90
Purchase #6	$224.53	13.597%	$255.0593	$255.06	$255.05	$255.10
Purchase #7	$193.53	12.402%	$217.5316	$217.53	$217.55	$217.50
7 purchase totals =	$1,264.36		$1,404.0574	$1,404.06	$1,404.00	$1,404.20