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	$59.84	9.546%	$65.5523	$65.55	$65.55	$65.60
Purchase #2	$195.42	3.589%	$202.4336	$202.43	$202.45	$202.40
Purchase #3	$110.86	11.612%	$123.7331	$123.73	$123.75	$123.70
Purchase #4	$219.60	4.149%	$228.7112	$228.71	$228.70	$228.70
Purchase #5	$200.93	4.753%	$210.4802	$210.48	$210.50	$210.50
Purchase #6	$131.59	12.836%	$148.4809	$148.48	$148.50	$148.50
Purchase #7	$29.70	12.554%	$33.4285	$33.43	$33.45	$33.40
7 purchase totals =	$947.94		$1,012.8198	$1,012.81	$1,012.90	$1,012.80