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	$90.99	8.471%	$98.6978	$98.70	$98.70	$98.70
Purchase #2	$176.87	7.837%	$190.7313	$190.73	$190.75	$190.70
Purchase #3	$200.64	7.701%	$216.0913	$216.09	$216.10	$216.10
Purchase #4	$99.55	11.781%	$111.278	$111.28	$111.30	$111.30
Purchase #5	$184.53	7.565%	$198.4897	$198.49	$198.50	$198.50
Purchase #6	$88.98	7.645%	$95.7825	$95.78	$95.80	$95.80
Purchase #7	$131.97	8.815%	$143.6032	$143.60	$143.60	$143.60
7 purchase totals =	$973.53		$1,054.6738	$1,054.67	$1,054.75	$1,054.70