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	$221.28	7.476%	$237.8229	$237.82	$237.80	$237.80
Purchase #2	$37.25	4.407%	$38.8916	$38.89	$38.90	$38.90
Purchase #3	$51.40	4.452%	$53.6883	$53.69	$53.70	$53.70
Purchase #4	$92.60	7.622%	$99.658	$99.66	$99.65	$99.70
Purchase #5	$165.65	13.657%	$188.2728	$188.27	$188.25	$188.30
Purchase #6	$248.35	4.245%	$258.8925	$258.89	$258.90	$258.90
Purchase #7	$200.38	4.634%	$209.6656	$209.67	$209.65	$209.70
7 purchase totals =	$1,016.91		$1,086.8917	$1,086.89	$1,086.85	$1,087.00