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	$107.34	4.176%	$111.8225	$111.82	$111.80	$111.80
Purchase #2	$41.98	3.106%	$43.2839	$43.28	$43.30	$43.30
Purchase #3	$6.73	6.817%	$7.1888	$7.19	$7.20	$7.20
Purchase #4	$32.36	13.290%	$36.6606	$36.66	$36.65	$36.70
Purchase #5	$236.76	3.732%	$245.5959	$245.60	$245.60	$245.60
Purchase #6	$103.29	8.251%	$111.8125	$111.81	$111.80	$111.80
Purchase #7	$137.52	5.412%	$144.9626	$144.96	$144.95	$145.00
7 purchase totals =	$665.98		$701.3268	$701.32	$701.30	$701.40