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	$177.63	9.467%	$194.4462	$194.45	$194.45	$194.40
Purchase #2	$207.72	6.457%	$221.1325	$221.13	$221.15	$221.10
Purchase #3	$205.76	12.632%	$231.7516	$231.75	$231.75	$231.80
Purchase #4	$35.31	10.360%	$38.9681	$38.97	$38.95	$39.00
Purchase #5	$55.53	12.560%	$62.5046	$62.50	$62.50	$62.50
Purchase #6	$145.88	13.454%	$165.5067	$165.51	$165.50	$165.50
Purchase #7	$132.68	9.720%	$145.5765	$145.58	$145.60	$145.60
7 purchase totals =	$960.51		$1,059.8862	$1,059.89	$1,059.90	$1,059.90