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	$97.52	4.568%	$101.9747	$101.97	$101.95	$102.00
Purchase #2	$19.54	4.549%	$20.4289	$20.43	$20.45	$20.40
Purchase #3	$9.85	3.105%	$10.1558	$10.16	$10.15	$10.20
Purchase #4	$86.47	3.612%	$89.5933	$89.59	$89.60	$89.60
Purchase #5	$24.43	3.310%	$25.2386	$25.24	$25.25	$25.20
Purchase #6	$196.86	10.874%	$218.2666	$218.27	$218.25	$218.30
Purchase #7	$84.41	13.838%	$96.0907	$96.09	$96.10	$96.10
7 purchase totals =	$519.08		$561.7486	$561.75	$561.75	$561.80