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	$222.66	4.735%	$233.203	$233.20	$233.20	$233.20
Purchase #2	$246.59	12.113%	$276.4594	$276.46	$276.45	$276.50
Purchase #3	$72.58	4.828%	$76.0842	$76.08	$76.10	$76.10
Purchase #4	$248.42	5.302%	$261.5912	$261.59	$261.60	$261.60
Purchase #5	$86.31	11.755%	$96.4557	$96.46	$96.45	$96.50
Purchase #6	$104.81	4.582%	$109.6124	$109.61	$109.60	$109.60
Purchase #7	$6.94	12.481%	$7.8062	$7.81	$7.80	$7.80
7 purchase totals =	$988.31		$1,061.2121	$1,061.21	$1,061.20	$1,061.30