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	$215.31	11.228%	$239.485	$239.49	$239.50	$239.50
Purchase #2	$67.57	6.336%	$71.8512	$71.85	$71.85	$71.90
Purchase #3	$65.42	8.474%	$70.9637	$70.96	$70.95	$71.00
Purchase #4	$203.75	6.710%	$217.4216	$217.42	$217.40	$217.40
Purchase #5	$155.46	4.286%	$162.123	$162.12	$162.10	$162.10
Purchase #6	$53.35	5.431%	$56.2474	$56.25	$56.25	$56.20
Purchase #7	$228.99	5.583%	$241.7745	$241.77	$241.75	$241.80
7 purchase totals =	$989.85		$1,059.8664	$1,059.86	$1,059.80	$1,059.90