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	$236.44	10.155%	$260.4505	$260.45	$260.45	$260.50
Purchase #2	$105.28	5.440%	$111.0072	$111.01	$111.00	$111.00
Purchase #3	$141.86	4.442%	$148.1614	$148.16	$148.15	$148.20
Purchase #4	$50.66	11.225%	$56.3466	$56.35	$56.35	$56.30
Purchase #5	$10.32	5.434%	$10.8808	$10.88	$10.90	$10.90
Purchase #6	$211.93	11.109%	$235.4733	$235.47	$235.45	$235.50
Purchase #7	$211.65	9.386%	$231.5155	$231.52	$231.50	$231.50
7 purchase totals =	$968.14		$1,053.8353	$1,053.84	$1,053.80	$1,053.90