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	$156.61	13.537%	$177.8103	$177.81	$177.80	$177.80
Purchase #2	$190.40	13.389%	$215.8927	$215.89	$215.90	$215.90
Purchase #3	$43.96	11.188%	$48.8782	$48.88	$48.90	$48.90
Purchase #4	$177.86	7.396%	$191.0145	$191.01	$191.00	$191.00
Purchase #5	$51.38	5.289%	$54.0975	$54.10	$54.10	$54.10
Purchase #6	$207.90	5.554%	$219.4468	$219.45	$219.45	$219.40
Purchase #7	$149.54	4.382%	$156.0928	$156.09	$156.10	$156.10
7 purchase totals =	$977.65		$1,063.2328	$1,063.23	$1,063.25	$1,063.20