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	$218.41	8.716%	$237.4466	$237.45	$237.45	$237.40
Purchase #2	$20.29	12.707%	$22.8683	$22.87	$22.85	$22.90
Purchase #3	$88.47	8.533%	$96.0191	$96.02	$96.00	$96.00
Purchase #4	$112.49	3.732%	$116.6881	$116.69	$116.70	$116.70
Purchase #5	$130.25	9.381%	$142.4688	$142.47	$142.45	$142.50
Purchase #6	$114.54	7.857%	$123.5394	$123.54	$123.55	$123.50
Purchase #7	$17.30	5.589%	$18.2669	$18.27	$18.25	$18.30
7 purchase totals =	$701.75		$757.2972	$757.31	$757.25	$757.30