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	$119.33	4.310%	$124.4731	$124.47	$124.45	$124.50
Purchase #2	$66.85	8.484%	$72.5216	$72.52	$72.50	$72.50
Purchase #3	$20.98	6.473%	$22.338	$22.34	$22.35	$22.30
Purchase #4	$113.79	11.687%	$127.0886	$127.09	$127.10	$127.10
Purchase #5	$249.77	4.421%	$260.8123	$260.81	$260.80	$260.80
Purchase #6	$218.65	7.263%	$234.5305	$234.53	$234.55	$234.50
Purchase #7	$202.62	9.322%	$221.5082	$221.51	$221.50	$221.50
7 purchase totals =	$991.99		$1,063.2723	$1,063.27	$1,063.25	$1,063.20