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	$152.53	3.477%	$157.8335	$157.83	$157.85	$157.80
Purchase #2	$12.46	10.492%	$13.7673	$13.77	$13.75	$13.80
Purchase #3	$185.81	12.431%	$208.908	$208.91	$208.90	$208.90
Purchase #4	$15.46	12.643%	$17.4146	$17.41	$17.40	$17.40
Purchase #5	$242.70	9.374%	$265.4507	$265.45	$265.45	$265.50
Purchase #6	$190.94	4.837%	$200.1758	$200.18	$200.20	$200.20
Purchase #7	$201.30	10.637%	$222.7123	$222.71	$222.70	$222.70
7 purchase totals =	$1,001.20		$1,086.2622	$1,086.26	$1,086.25	$1,086.30