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	$236.94	10.646%	$262.1646	$262.16	$262.15	$262.20
Purchase #2	$147.36	10.602%	$162.9831	$162.98	$163.00	$163.00
Purchase #3	$42.75	3.441%	$44.221	$44.22	$44.20	$44.20
Purchase #4	$36.41	12.470%	$40.9503	$40.95	$40.95	$41.00
Purchase #5	$216.64	7.788%	$233.5119	$233.51	$233.50	$233.50
Purchase #6	$97.26	3.567%	$100.7293	$100.73	$100.75	$100.70
Purchase #7	$156.94	9.776%	$172.2825	$172.28	$172.30	$172.30
7 purchase totals =	$934.30		$1,016.8427	$1,016.83	$1,016.85	$1,016.90