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	$179.63	8.530%	$194.9524	$194.95	$194.95	$195.00
Purchase #2	$205.81	7.154%	$220.5336	$220.53	$220.55	$220.50
Purchase #3	$50.54	3.406%	$52.2614	$52.26	$52.25	$52.30
Purchase #4	$236.71	7.671%	$254.868	$254.87	$254.85	$254.90
Purchase #5	$65.74	10.287%	$72.5027	$72.50	$72.50	$72.50
Purchase #6	$18.70	11.563%	$20.8623	$20.86	$20.85	$20.90
Purchase #7	$176.61	9.767%	$193.8595	$193.86	$193.85	$193.90
7 purchase totals =	$933.74		$1,009.8399	$1,009.83	$1,009.80	$1,010.00