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	$130.66	11.452%	$145.6232	$145.62	$145.60	$145.60
Purchase #2	$112.56	5.169%	$118.3782	$118.38	$118.40	$118.40
Purchase #3	$96.62	6.538%	$102.937	$102.94	$102.95	$102.90
Purchase #4	$244.60	11.468%	$272.6507	$272.65	$272.65	$272.70
Purchase #5	$125.33	4.482%	$130.9473	$130.95	$130.95	$130.90
Purchase #6	$151.58	8.485%	$164.4416	$164.44	$164.45	$164.40
Purchase #7	$233.39	13.744%	$265.4671	$265.47	$265.45	$265.50
7 purchase totals =	$1,094.74		$1,200.4451	$1,200.45	$1,200.45	$1,200.40