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	$187.36	11.572%	$209.0413	$209.04	$209.05	$209.00
Purchase #2	$145.45	7.111%	$155.7929	$155.79	$155.80	$155.80
Purchase #3	$46.63	10.386%	$51.473	$51.47	$51.45	$51.50
Purchase #4	$158.95	11.108%	$176.6062	$176.61	$176.60	$176.60
Purchase #5	$86.90	6.198%	$92.2861	$92.29	$92.30	$92.30
Purchase #6	$156.82	9.105%	$171.0985	$171.10	$171.10	$171.10
Purchase #7	$182.57	4.293%	$190.4077	$190.41	$190.40	$190.40
7 purchase totals =	$964.68		$1,046.7057	$1,046.71	$1,046.70	$1,046.70