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	$231.57	13.511%	$262.8574	$262.86	$262.85	$262.90
Purchase #2	$26.69	10.442%	$29.477	$29.48	$29.50	$29.50
Purchase #3	$48.87	10.797%	$54.1465	$54.15	$54.15	$54.10
Purchase #4	$113.81	7.167%	$121.9668	$121.97	$121.95	$122.00
Purchase #5	$206.27	13.173%	$233.4419	$233.44	$233.45	$233.40
Purchase #6	$95.36	5.103%	$100.2262	$100.23	$100.25	$100.20
Purchase #7	$238.66	9.683%	$261.7694	$261.77	$261.75	$261.80
7 purchase totals =	$961.23		$1,063.8852	$1,063.90	$1,063.90	$1,063.90