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	$90.74	4.666%	$94.9739	$94.97	$94.95	$95.00
Purchase #2	$139.40	13.519%	$158.2455	$158.25	$158.25	$158.20
Purchase #3	$159.61	5.641%	$168.6136	$168.61	$168.60	$168.60
Purchase #4	$124.71	9.541%	$136.6086	$136.61	$136.60	$136.60
Purchase #5	$143.32	13.612%	$162.8287	$162.83	$162.85	$162.80
Purchase #6	$6.29	12.764%	$7.0929	$7.09	$7.10	$7.10
Purchase #7	$46.70	9.428%	$51.1029	$51.10	$51.10	$51.10
7 purchase totals =	$710.77		$779.4661	$779.46	$779.45	$779.40