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	$148.57	4.794%	$155.6924	$155.69	$155.70	$155.70
Purchase #2	$165.78	13.408%	$188.0078	$188.01	$188.00	$188.00
Purchase #3	$68.62	6.253%	$72.9108	$72.91	$72.90	$72.90
Purchase #4	$138.60	9.533%	$151.8127	$151.81	$151.80	$151.80
Purchase #5	$158.81	3.559%	$164.462	$164.46	$164.45	$164.50
Purchase #6	$139.32	13.594%	$158.2592	$158.26	$158.25	$158.30
Purchase #7	$47.66	12.161%	$53.4559	$53.46	$53.45	$53.50
7 purchase totals =	$867.36		$944.6008	$944.60	$944.55	$944.70