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	$119.47	6.187%	$126.8616	$126.86	$126.85	$126.90
Purchase #2	$112.37	10.356%	$124.007	$124.01	$124.00	$124.00
Purchase #3	$245.67	4.162%	$255.8948	$255.89	$255.90	$255.90
Purchase #4	$24.75	4.154%	$25.7781	$25.78	$25.80	$25.80
Purchase #5	$89.88	10.660%	$99.4612	$99.46	$99.45	$99.50
Purchase #6	$183.52	8.707%	$199.4991	$199.50	$199.50	$199.50
Purchase #7	$125.69	3.561%	$130.1658	$130.17	$130.15	$130.20
7 purchase totals =	$901.35		$961.6676	$961.67	$961.65	$961.80