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	$112.27	5.421%	$118.3562	$118.36	$118.35	$118.40
Purchase #2	$135.63	11.421%	$151.1203	$151.12	$151.10	$151.10
Purchase #3	$37.52	8.581%	$40.7396	$40.74	$40.75	$40.70
Purchase #4	$85.55	8.172%	$92.5411	$92.54	$92.55	$92.50
Purchase #5	$97.54	8.258%	$105.5949	$105.59	$105.60	$105.60
Purchase #6	$176.45	4.449%	$184.3003	$184.30	$184.30	$184.30
Purchase #7	$92.87	10.269%	$102.4068	$102.41	$102.40	$102.40
7 purchase totals =	$737.83		$795.0592	$795.06	$795.05	$795.00