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	$185.61	5.312%	$195.4696	$195.47	$195.45	$195.50
Purchase #2	$60.90	9.751%	$66.8384	$66.84	$66.85	$66.80
Purchase #3	$37.55	6.625%	$40.0377	$40.04	$40.05	$40.00
Purchase #4	$159.33	5.491%	$168.0788	$168.08	$168.10	$168.10
Purchase #5	$82.83	10.536%	$91.557	$91.56	$91.55	$91.60
Purchase #6	$114.69	4.183%	$119.4875	$119.49	$119.50	$119.50
Purchase #7	$22.83	9.565%	$25.0137	$25.01	$25.00	$25.00
7 purchase totals =	$663.74		$706.4827	$706.49	$706.50	$706.50