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	$200.39	5.607%	$211.6259	$211.63	$211.65	$211.60
Purchase #2	$160.42	7.152%	$171.8932	$171.89	$171.90	$171.90
Purchase #3	$192.33	6.591%	$205.0065	$205.01	$205.00	$205.00
Purchase #4	$185.58	8.244%	$200.8792	$200.88	$200.90	$200.90
Purchase #5	$151.89	13.496%	$172.3891	$172.39	$172.40	$172.40
Purchase #6	$120.48	13.382%	$136.6026	$136.60	$136.60	$136.60
Purchase #7	$150.71	11.806%	$168.5028	$168.50	$168.50	$168.50
7 purchase totals =	$1,161.80		$1,266.8993	$1,266.90	$1,266.95	$1,266.90