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	$182.61	10.151%	$201.1467	$201.15	$201.15	$201.10
Purchase #2	$133.79	10.687%	$148.0881	$148.09	$148.10	$148.10
Purchase #3	$50.78	6.304%	$53.9812	$53.98	$54.00	$54.00
Purchase #4	$111.86	13.105%	$126.5193	$126.52	$126.50	$126.50
Purchase #5	$89.76	11.591%	$100.1641	$100.16	$100.15	$100.20
Purchase #6	$55.81	13.831%	$63.5291	$63.53	$63.55	$63.50
Purchase #7	$223.98	13.809%	$254.9094	$254.91	$254.90	$254.90
7 purchase totals =	$848.59		$948.3379	$948.34	$948.35	$948.30