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	$90.65	5.867%	$95.9684	$95.97	$95.95	$96.00
Purchase #2	$214.61	12.314%	$241.0371	$241.04	$241.05	$241.00
Purchase #3	$149.89	12.407%	$168.4869	$168.49	$168.50	$168.50
Purchase #4	$144.26	10.291%	$159.1058	$159.11	$159.10	$159.10
Purchase #5	$91.82	8.724%	$99.8304	$99.83	$99.85	$99.80
Purchase #6	$83.63	11.221%	$93.0141	$93.01	$93.00	$93.00
Purchase #7	$224.41	13.623%	$254.9814	$254.98	$255.00	$255.00
7 purchase totals =	$999.27		$1,112.4241	$1,112.43	$1,112.45	$1,112.40