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	$130.90	9.677%	$143.5672	$143.57	$143.55	$143.60
Purchase #2	$213.90	8.736%	$232.5863	$232.59	$232.60	$232.60
Purchase #3	$208.82	3.423%	$215.9679	$215.97	$215.95	$216.00
Purchase #4	$105.57	5.655%	$111.54	$111.54	$111.55	$111.50
Purchase #5	$53.47	6.487%	$56.9386	$56.94	$56.95	$56.90
Purchase #6	$110.25	7.747%	$118.7911	$118.79	$118.80	$118.80
Purchase #7	$243.88	4.629%	$255.1692	$255.17	$255.15	$255.20
7 purchase totals =	$1,066.79		$1,134.5603	$1,134.57	$1,134.55	$1,134.60