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	$58.41	7.133%	$62.5764	$62.58	$62.60	$62.60
Purchase #2	$163.62	4.806%	$171.4836	$171.48	$171.50	$171.50
Purchase #3	$248.67	12.779%	$280.4475	$280.45	$280.45	$280.40
Purchase #4	$249.52	6.104%	$264.7507	$264.75	$264.75	$264.80
Purchase #5	$180.99	7.654%	$194.843	$194.84	$194.85	$194.80
Purchase #6	$58.50	6.863%	$62.5149	$62.51	$62.50	$62.50
Purchase #7	$38.35	6.612%	$40.8857	$40.89	$40.90	$40.90
7 purchase totals =	$998.06		$1,077.5018	$1,077.50	$1,077.55	$1,077.50