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	$56.56	8.799%	$61.5367	$61.54	$61.55	$61.50
Purchase #2	$56.75	12.546%	$63.8699	$63.87	$63.85	$63.90
Purchase #3	$159.89	7.763%	$172.3023	$172.30	$172.30	$172.30
Purchase #4	$31.95	10.343%	$35.2546	$35.25	$35.25	$35.30
Purchase #5	$204.68	6.299%	$217.5728	$217.57	$217.55	$217.60
Purchase #6	$233.72	3.600%	$242.1339	$242.13	$242.15	$242.10
Purchase #7	$250.46	4.522%	$261.7858	$261.79	$261.80	$261.80
7 purchase totals =	$994.01		$1,054.4560	$1,054.45	$1,054.45	$1,054.50