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	$178.30	7.611%	$191.8704	$191.87	$191.85	$191.90
Purchase #2	$213.83	9.597%	$234.3513	$234.35	$234.35	$234.40
Purchase #3	$220.94	6.574%	$235.4646	$235.46	$235.45	$235.50
Purchase #4	$41.29	10.319%	$45.5507	$45.55	$45.55	$45.60
Purchase #5	$78.64	4.772%	$82.3927	$82.39	$82.40	$82.40
Purchase #6	$237.69	6.473%	$253.0757	$253.08	$253.10	$253.10
Purchase #7	$104.95	6.826%	$112.1139	$112.11	$112.10	$112.10
7 purchase totals =	$1,075.64		$1,154.8193	$1,154.81	$1,154.80	$1,155.00