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	$209.62	4.369%	$218.7783	$218.78	$218.80	$218.80
Purchase #2	$129.69	11.538%	$144.6536	$144.65	$144.65	$144.70
Purchase #3	$128.56	10.854%	$142.5139	$142.51	$142.50	$142.50
Purchase #4	$82.87	6.804%	$88.5085	$88.51	$88.50	$88.50
Purchase #5	$115.55	6.851%	$123.4663	$123.47	$123.45	$123.50
Purchase #6	$223.75	4.556%	$233.9441	$233.94	$233.95	$233.90
Purchase #7	$104.49	10.723%	$115.6945	$115.69	$115.70	$115.70
7 purchase totals =	$994.53		$1,067.5592	$1,067.55	$1,067.55	$1,067.60