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	$138.42	3.261%	$142.9339	$142.93	$142.95	$142.90
Purchase #2	$175.53	8.557%	$190.5501	$190.55	$190.55	$190.60
Purchase #3	$48.75	3.288%	$50.3529	$50.35	$50.35	$50.40
Purchase #4	$106.89	4.271%	$111.4553	$111.46	$111.45	$111.50
Purchase #5	$232.67	4.836%	$243.9219	$243.92	$243.90	$243.90
Purchase #6	$195.52	4.587%	$204.4885	$204.49	$204.50	$204.50
Purchase #7	$104.55	12.792%	$117.924	$117.92	$117.90	$117.90
7 purchase totals =	$1,002.33		$1,061.6266	$1,061.62	$1,061.60	$1,061.70