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	$181.43	13.799%	$206.4655	$206.47	$206.45	$206.50
Purchase #2	$57.92	6.605%	$61.7456	$61.75	$61.75	$61.70
Purchase #3	$72.46	6.372%	$77.0772	$77.08	$77.10	$77.10
Purchase #4	$105.89	6.120%	$112.3705	$112.37	$112.35	$112.40
Purchase #5	$225.30	9.522%	$246.7531	$246.75	$246.75	$246.80
Purchase #6	$242.80	4.239%	$253.0923	$253.09	$253.10	$253.10
Purchase #7	$92.42	12.362%	$103.845	$103.85	$103.85	$103.80
7 purchase totals =	$978.22		$1,061.3492	$1,061.36	$1,061.35	$1,061.40