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	$83.39	3.698%	$86.4738	$86.47	$86.45	$86.50
Purchase #2	$105.50	10.135%	$116.1924	$116.19	$116.20	$116.20
Purchase #3	$192.87	8.149%	$208.587	$208.59	$208.60	$208.60
Purchase #4	$200.86	9.869%	$220.6829	$220.68	$220.70	$220.70
Purchase #5	$77.33	4.111%	$80.509	$80.51	$80.50	$80.50
Purchase #6	$56.76	4.274%	$59.1859	$59.19	$59.20	$59.20
Purchase #7	$249.86	12.589%	$281.3149	$281.31	$281.30	$281.30
7 purchase totals =	$966.57		$1,052.9459	$1,052.94	$1,052.95	$1,053.00