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	$151.46	3.629%	$156.9565	$156.96	$156.95	$157.00
Purchase #2	$40.41	12.162%	$45.3247	$45.32	$45.30	$45.30
Purchase #3	$205.81	3.337%	$212.6779	$212.68	$212.70	$212.70
Purchase #4	$60.38	4.825%	$63.2933	$63.29	$63.30	$63.30
Purchase #5	$13.61	5.558%	$14.3664	$14.37	$14.35	$14.40
Purchase #6	$200.39	4.242%	$208.8905	$208.89	$208.90	$208.90
Purchase #7	$93.80	7.421%	$100.7609	$100.76	$100.75	$100.80
7 purchase totals =	$765.86		$802.2702	$802.27	$802.25	$802.40