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	$192.39	11.152%	$213.8453	$213.85	$213.85	$213.80
Purchase #2	$164.42	9.524%	$180.0794	$180.08	$180.10	$180.10
Purchase #3	$139.85	6.196%	$148.5151	$148.52	$148.50	$148.50
Purchase #4	$193.82	11.137%	$215.4057	$215.41	$215.40	$215.40
Purchase #5	$96.35	12.721%	$108.6067	$108.61	$108.60	$108.60
Purchase #6	$99.95	10.110%	$110.0549	$110.05	$110.05	$110.10
Purchase #7	$82.72	5.123%	$86.9577	$86.96	$86.95	$87.00
7 purchase totals =	$969.50		$1,063.4648	$1,063.48	$1,063.45	$1,063.50