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	$24.30	5.357%	$25.6018	$25.60	$25.60	$25.60
Purchase #2	$88.58	8.318%	$95.9481	$95.95	$95.95	$95.90
Purchase #3	$119.42	9.812%	$131.1375	$131.14	$131.15	$131.10
Purchase #4	$94.91	11.386%	$105.7165	$105.72	$105.70	$105.70
Purchase #5	$236.25	12.565%	$265.9348	$265.93	$265.95	$265.90
Purchase #6	$193.48	12.203%	$217.0904	$217.09	$217.10	$217.10
Purchase #7	$208.50	5.517%	$220.0029	$220.00	$220.00	$220.00
7 purchase totals =	$965.44		$1,061.4320	$1,061.43	$1,061.45	$1,061.30