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	$103.62	12.747%	$116.8284	$116.83	$116.85	$116.80
Purchase #2	$190.79	3.184%	$196.8648	$196.86	$196.85	$196.90
Purchase #3	$6.69	9.397%	$7.3187	$7.32	$7.30	$7.30
Purchase #4	$234.37	5.633%	$247.5721	$247.57	$247.55	$247.60
Purchase #5	$156.80	4.467%	$163.8043	$163.80	$163.80	$163.80
Purchase #6	$227.40	3.152%	$234.5676	$234.57	$234.55	$234.60
Purchase #7	$53.56	10.509%	$59.1886	$59.19	$59.20	$59.20
7 purchase totals =	$973.23		$1,026.1445	$1,026.14	$1,026.10	$1,026.20