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	$115.89	8.267%	$125.4706	$125.47	$125.45	$125.50
Purchase #2	$133.61	6.285%	$142.0074	$142.01	$142.00	$142.00
Purchase #3	$213.41	4.337%	$222.6656	$222.67	$222.65	$222.70
Purchase #4	$161.97	7.320%	$173.8262	$173.83	$173.85	$173.80
Purchase #5	$150.76	12.405%	$169.4618	$169.46	$169.45	$169.50
Purchase #6	$127.93	10.304%	$141.1119	$141.11	$141.10	$141.10
Purchase #7	$172.72	6.502%	$183.9503	$183.95	$183.95	$184.00
7 purchase totals =	$1,076.29		$1,158.4938	$1,158.50	$1,158.45	$1,158.60