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	$213.36	6.611%	$227.4652	$227.47	$227.45	$227.50
Purchase #2	$152.44	9.143%	$166.3776	$166.38	$166.40	$166.40
Purchase #3	$46.46	12.844%	$52.4273	$52.43	$52.45	$52.40
Purchase #4	$103.63	7.657%	$111.5649	$111.56	$111.55	$111.60
Purchase #5	$119.29	5.764%	$126.1659	$126.17	$126.15	$126.20
Purchase #6	$245.80	5.737%	$259.9015	$259.90	$259.90	$259.90
Purchase #7	$66.25	10.544%	$73.2354	$73.24	$73.25	$73.20
7 purchase totals =	$947.23		$1,017.1378	$1,017.15	$1,017.15	$1,017.20