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	$79.28	8.325%	$85.8801	$85.88	$85.90	$85.90
Purchase #2	$172.53	10.127%	$190.0021	$190.00	$190.00	$190.00
Purchase #3	$241.94	3.625%	$250.7103	$250.71	$250.70	$250.70
Purchase #4	$159.53	8.196%	$172.6051	$172.61	$172.60	$172.60
Purchase #5	$140.42	10.237%	$154.7948	$154.79	$154.80	$154.80
Purchase #6	$38.69	4.328%	$40.3645	$40.36	$40.35	$40.40
Purchase #7	$225.90	5.160%	$237.5564	$237.56	$237.55	$237.60
7 purchase totals =	$1,058.29		$1,131.9133	$1,131.91	$1,131.90	$1,132.00