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	$126.60	5.125%	$133.0883	$133.09	$133.10	$133.10
Purchase #2	$103.27	5.623%	$109.0769	$109.08	$109.10	$109.10
Purchase #3	$63.41	5.748%	$67.0548	$67.05	$67.05	$67.10
Purchase #4	$54.25	9.832%	$59.5839	$59.58	$59.60	$59.60
Purchase #5	$207.33	8.784%	$225.5419	$225.54	$225.55	$225.50
Purchase #6	$137.88	6.327%	$146.6037	$146.60	$146.60	$146.60
Purchase #7	$23.82	5.126%	$25.041	$25.04	$25.05	$25.00
7 purchase totals =	$716.56		$765.9905	$765.98	$766.05	$766.00