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	$65.75	8.616%	$71.415	$71.42	$71.40	$71.40
Purchase #2	$93.96	7.269%	$100.79	$100.79	$100.80	$100.80
Purchase #3	$241.45	7.113%	$258.6243	$258.62	$258.60	$258.60
Purchase #4	$38.54	12.226%	$43.2519	$43.25	$43.25	$43.30
Purchase #5	$112.93	9.421%	$123.5691	$123.57	$123.55	$123.60
Purchase #6	$157.76	9.781%	$173.1905	$173.19	$173.20	$173.20
Purchase #7	$22.85	6.131%	$24.2509	$24.25	$24.25	$24.30
7 purchase totals =	$733.24		$795.0917	$795.09	$795.05	$795.20