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	$132.83	12.119%	$148.9277	$148.93	$148.95	$148.90
Purchase #2	$40.27	9.103%	$43.9358	$43.94	$43.95	$43.90
Purchase #3	$18.70	9.225%	$20.4251	$20.43	$20.45	$20.40
Purchase #4	$159.48	7.301%	$171.1236	$171.12	$171.10	$171.10
Purchase #5	$189.87	3.494%	$196.5041	$196.50	$196.50	$196.50
Purchase #6	$83.84	3.801%	$87.0268	$87.03	$87.05	$87.00
Purchase #7	$60.71	6.105%	$64.4163	$64.42	$64.40	$64.40
7 purchase totals =	$685.70		$732.3594	$732.37	$732.40	$732.20