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	$91.81	5.707%	$97.0496	$97.05	$97.05	$97.00
Purchase #2	$116.61	5.642%	$123.1891	$123.19	$123.20	$123.20
Purchase #3	$176.70	13.712%	$200.9291	$200.93	$200.95	$200.90
Purchase #4	$153.32	7.634%	$165.0244	$165.02	$165.00	$165.00
Purchase #5	$184.67	6.417%	$196.5203	$196.52	$196.50	$196.50
Purchase #6	$30.96	5.549%	$32.678	$32.68	$32.70	$32.70
Purchase #7	$132.72	4.757%	$139.0335	$139.03	$139.05	$139.00
7 purchase totals =	$886.79		$954.4240	$954.42	$954.45	$954.30