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	$207.36	6.607%	$221.0603	$221.06	$221.05	$221.10
Purchase #2	$14.89	6.595%	$15.872	$15.87	$15.85	$15.90
Purchase #3	$95.60	6.653%	$101.9603	$101.96	$101.95	$102.00
Purchase #4	$134.72	6.744%	$143.8055	$143.81	$143.80	$143.80
Purchase #5	$116.89	12.622%	$131.6439	$131.64	$131.65	$131.60
Purchase #6	$158.72	5.256%	$167.0623	$167.06	$167.05	$167.10
Purchase #7	$222.55	12.516%	$250.4044	$250.40	$250.40	$250.40
7 purchase totals =	$950.73		$1,031.8087	$1,031.80	$1,031.75	$1,031.90