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	$57.36	8.715%	$62.3589	$62.36	$62.35	$62.40
Purchase #2	$249.82	12.139%	$280.1456	$280.15	$280.15	$280.10
Purchase #3	$84.96	13.687%	$96.5885	$96.59	$96.60	$96.60
Purchase #4	$213.58	10.265%	$235.504	$235.50	$235.50	$235.50
Purchase #5	$197.74	12.553%	$222.5623	$222.56	$222.55	$222.60
Purchase #6	$96.90	3.462%	$100.2547	$100.25	$100.25	$100.30
Purchase #7	$34.88	10.461%	$38.5288	$38.53	$38.55	$38.50
7 purchase totals =	$935.24		$1,035.9428	$1,035.94	$1,035.95	$1,036.00