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	$183.59	13.602%	$208.5619	$208.56	$208.55	$208.60
Purchase #2	$163.27	12.762%	$184.1065	$184.11	$184.10	$184.10
Purchase #3	$134.30	10.312%	$148.149	$148.15	$148.15	$148.10
Purchase #4	$114.86	9.556%	$125.836	$125.84	$125.85	$125.80
Purchase #5	$189.69	5.772%	$200.6389	$200.64	$200.65	$200.60
Purchase #6	$238.55	9.814%	$261.9613	$261.96	$261.95	$262.00
Purchase #7	$19.37	10.221%	$21.3498	$21.35	$21.35	$21.30
7 purchase totals =	$1,043.63		$1,150.6034	$1,150.61	$1,150.60	$1,150.50