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	$203.29	4.287%	$212.005	$212.01	$212.00	$212.00
Purchase #2	$35.33	6.578%	$37.654	$37.65	$37.65	$37.70
Purchase #3	$54.26	9.261%	$59.285	$59.29	$59.30	$59.30
Purchase #4	$231.88	10.330%	$255.8332	$255.83	$255.85	$255.80
Purchase #5	$143.70	5.112%	$151.0459	$151.05	$151.05	$151.00
Purchase #6	$126.27	9.745%	$138.575	$138.58	$138.60	$138.60
Purchase #7	$208.76	7.798%	$225.0391	$225.04	$225.05	$225.00
7 purchase totals =	$1,003.49		$1,079.4372	$1,079.45	$1,079.50	$1,079.40