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	$215.51	12.150%	$241.6945	$241.69	$241.70	$241.70
Purchase #2	$223.96	4.472%	$233.9755	$233.98	$234.00	$234.00
Purchase #3	$153.98	9.384%	$168.4295	$168.43	$168.45	$168.40
Purchase #4	$29.28	11.642%	$32.6888	$32.69	$32.70	$32.70
Purchase #5	$87.59	5.296%	$92.2288	$92.23	$92.25	$92.20
Purchase #6	$232.28	13.438%	$263.4938	$263.49	$263.50	$263.50
Purchase #7	$56.93	9.780%	$62.4978	$62.50	$62.50	$62.50
7 purchase totals =	$999.53		$1,095.0087	$1,095.01	$1,095.10	$1,095.00