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	$134.29	10.840%	$148.847	$148.85	$148.85	$148.80
Purchase #2	$172.31	13.297%	$195.2221	$195.22	$195.20	$195.20
Purchase #3	$217.88	5.842%	$230.6085	$230.61	$230.60	$230.60
Purchase #4	$183.54	3.839%	$190.5861	$190.59	$190.60	$190.60
Purchase #5	$63.97	10.398%	$70.6216	$70.62	$70.60	$70.60
Purchase #6	$99.53	4.516%	$104.0248	$104.02	$104.00	$104.00
Purchase #7	$78.76	8.712%	$85.6216	$85.62	$85.60	$85.60
7 purchase totals =	$950.28		$1,025.5317	$1,025.53	$1,025.45	$1,025.40