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	$193.72	6.351%	$206.0232	$206.02	$206.00	$206.00
Purchase #2	$41.26	5.572%	$43.559	$43.56	$43.55	$43.60
Purchase #3	$115.28	7.165%	$123.5398	$123.54	$123.55	$123.50
Purchase #4	$175.25	9.321%	$191.5851	$191.59	$191.60	$191.60
Purchase #5	$124.64	4.174%	$129.8425	$129.84	$129.85	$129.80
Purchase #6	$114.31	3.754%	$118.6012	$118.60	$118.60	$118.60
Purchase #7	$10.63	4.849%	$11.1454	$11.15	$11.15	$11.10
7 purchase totals =	$775.09		$824.2962	$824.30	$824.30	$824.20