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	$50.42	4.785%	$52.8326	$52.83	$52.85	$52.80
Purchase #2	$247.48	7.136%	$265.1402	$265.14	$265.15	$265.10
Purchase #3	$160.61	7.634%	$172.871	$172.87	$172.85	$172.90
Purchase #4	$214.86	10.426%	$237.2613	$237.26	$237.25	$237.30
Purchase #5	$142.45	13.641%	$161.8816	$161.88	$161.90	$161.90
Purchase #6	$28.47	10.190%	$31.3711	$31.37	$31.35	$31.40
Purchase #7	$231.77	4.225%	$241.5623	$241.56	$241.55	$241.60
7 purchase totals =	$1,076.06		$1,162.9201	$1,162.91	$1,162.90	$1,163.00