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	$210.64	13.750%	$239.603	$239.60	$239.60	$239.60
Purchase #2	$66.86	9.528%	$73.2304	$73.23	$73.25	$73.20
Purchase #3	$164.71	12.491%	$185.2839	$185.28	$185.30	$185.30
Purchase #4	$116.37	12.456%	$130.865	$130.87	$130.85	$130.90
Purchase #5	$159.42	4.618%	$166.782	$166.78	$166.80	$166.80
Purchase #6	$179.80	4.515%	$187.918	$187.92	$187.90	$187.90
Purchase #7	$134.64	3.660%	$139.5678	$139.57	$139.55	$139.60
7 purchase totals =	$1,032.44		$1,123.2501	$1,123.25	$1,123.25	$1,123.30