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	$233.82	12.132%	$262.187	$262.19	$262.20	$262.20
Purchase #2	$61.51	4.127%	$64.0485	$64.05	$64.05	$64.00
Purchase #3	$39.58	3.459%	$40.9491	$40.95	$40.95	$40.90
Purchase #4	$242.45	5.399%	$255.5399	$255.54	$255.55	$255.50
Purchase #5	$93.92	12.433%	$105.5971	$105.60	$105.60	$105.60
Purchase #6	$240.79	9.201%	$262.9451	$262.95	$262.95	$262.90
Purchase #7	$93.98	13.179%	$106.3656	$106.37	$106.35	$106.40
7 purchase totals =	$1,006.05		$1,097.6323	$1,097.65	$1,097.65	$1,097.50