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	$119.46	12.424%	$134.3017	$134.30	$134.30	$134.30
Purchase #2	$215.80	3.167%	$222.6344	$222.63	$222.65	$222.60
Purchase #3	$167.80	8.746%	$182.4758	$182.48	$182.50	$182.50
Purchase #4	$238.90	11.624%	$266.6697	$266.67	$266.65	$266.70
Purchase #5	$94.60	5.546%	$99.8465	$99.85	$99.85	$99.80
Purchase #6	$101.32	10.741%	$112.2028	$112.20	$112.20	$112.20
Purchase #7	$157.98	13.871%	$179.8934	$179.89	$179.90	$179.90
7 purchase totals =	$1,095.86		$1,198.0243	$1,198.02	$1,198.05	$1,198.00