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	$173.61	12.611%	$195.504	$195.50	$195.50	$195.50
Purchase #2	$31.61	13.278%	$35.8072	$35.81	$35.80	$35.80
Purchase #3	$159.97	12.675%	$180.2462	$180.25	$180.25	$180.20
Purchase #4	$89.95	12.590%	$101.2747	$101.27	$101.25	$101.30
Purchase #5	$56.66	12.257%	$63.6048	$63.60	$63.60	$63.60
Purchase #6	$51.52	3.532%	$53.3397	$53.34	$53.35	$53.30
Purchase #7	$100.71	10.842%	$111.629	$111.63	$111.65	$111.60
7 purchase totals =	$664.03		$741.4056	$741.40	$741.40	$741.30