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	$221.76	4.375%	$231.462	$231.46	$231.45	$231.50
Purchase #2	$91.69	11.411%	$102.1527	$102.15	$102.15	$102.20
Purchase #3	$137.76	9.848%	$151.3266	$151.33	$151.35	$151.30
Purchase #4	$221.85	8.790%	$241.3506	$241.35	$241.35	$241.40
Purchase #5	$30.41	6.160%	$32.2833	$32.28	$32.30	$32.30
Purchase #6	$189.52	5.430%	$199.8109	$199.81	$199.80	$199.80
Purchase #7	$82.83	4.323%	$86.4107	$86.41	$86.40	$86.40
7 purchase totals =	$975.82		$1,044.7968	$1,044.79	$1,044.80	$1,044.90