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	$182.96	5.252%	$192.5691	$192.57	$192.55	$192.60
Purchase #2	$211.41	4.185%	$220.2575	$220.26	$220.25	$220.30
Purchase #3	$137.48	3.613%	$142.4472	$142.45	$142.45	$142.40
Purchase #4	$154.94	10.782%	$171.6456	$171.65	$171.65	$171.60
Purchase #5	$162.72	6.252%	$172.8933	$172.89	$172.90	$172.90
Purchase #6	$92.82	13.866%	$105.6904	$105.69	$105.70	$105.70
Purchase #7	$203.81	13.786%	$231.9072	$231.91	$231.90	$231.90
7 purchase totals =	$1,146.14		$1,237.4103	$1,237.42	$1,237.40	$1,237.40