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	$132.95	5.178%	$139.8342	$139.83	$139.85	$139.80
Purchase #2	$158.25	11.532%	$176.4994	$176.50	$176.50	$176.50
Purchase #3	$12.26	13.367%	$13.8988	$13.90	$13.90	$13.90
Purchase #4	$150.54	12.812%	$169.8272	$169.83	$169.85	$169.80
Purchase #5	$205.30	5.130%	$215.8319	$215.83	$215.85	$215.80
Purchase #6	$24.32	4.430%	$25.3974	$25.40	$25.40	$25.40
Purchase #7	$165.76	10.865%	$183.7698	$183.77	$183.75	$183.80
7 purchase totals =	$849.38		$925.0587	$925.06	$925.10	$925.00