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	$195.74	5.103%	$205.7286	$205.73	$205.75	$205.70
Purchase #2	$69.98	5.535%	$73.8534	$73.85	$73.85	$73.90
Purchase #3	$230.98	11.835%	$258.3165	$258.32	$258.30	$258.30
Purchase #4	$52.38	4.275%	$54.6192	$54.62	$54.60	$54.60
Purchase #5	$101.54	6.281%	$107.9177	$107.92	$107.90	$107.90
Purchase #6	$129.37	10.210%	$142.5787	$142.58	$142.60	$142.60
Purchase #7	$153.46	7.425%	$164.8544	$164.85	$164.85	$164.90
7 purchase totals =	$933.45		$1,007.8685	$1,007.87	$1,007.85	$1,007.90