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	$213.70	9.698%	$234.4246	$234.42	$234.40	$234.40
Purchase #2	$236.79	9.111%	$258.3639	$258.36	$258.35	$258.40
Purchase #3	$27.55	6.464%	$29.3308	$29.33	$29.35	$29.30
Purchase #4	$97.71	13.176%	$110.5843	$110.58	$110.60	$110.60
Purchase #5	$19.53	4.549%	$20.4184	$20.42	$20.40	$20.40
Purchase #6	$212.40	6.162%	$225.4881	$225.49	$225.50	$225.50
Purchase #7	$133.50	3.256%	$137.8468	$137.85	$137.85	$137.80
7 purchase totals =	$941.18		$1,016.4569	$1,016.45	$1,016.45	$1,016.40