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	$190.73	8.520%	$206.9802	$206.98	$207.00	$207.00
Purchase #2	$207.45	7.242%	$222.4735	$222.47	$222.45	$222.50
Purchase #3	$204.66	6.352%	$217.66	$217.66	$217.65	$217.70
Purchase #4	$130.83	10.587%	$144.681	$144.68	$144.70	$144.70
Purchase #5	$112.27	7.405%	$120.5836	$120.58	$120.60	$120.60
Purchase #6	$151.73	4.440%	$158.4668	$158.47	$158.45	$158.50
Purchase #7	$37.56	12.623%	$42.3012	$42.30	$42.30	$42.30
7 purchase totals =	$1,035.23		$1,113.1463	$1,113.14	$1,113.15	$1,113.30