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	$165.25	12.457%	$185.8352	$185.84	$185.85	$185.80
Purchase #2	$24.68	7.706%	$26.5818	$26.58	$26.60	$26.60
Purchase #3	$66.80	8.387%	$72.4025	$72.40	$72.40	$72.40
Purchase #4	$217.61	5.119%	$228.7495	$228.75	$228.75	$228.70
Purchase #5	$163.89	4.784%	$171.7305	$171.73	$171.75	$171.70
Purchase #6	$59.67	12.741%	$67.2726	$67.27	$67.25	$67.30
Purchase #7	$11.45	9.797%	$12.5718	$12.57	$12.55	$12.60
7 purchase totals =	$709.35		$765.1439	$765.14	$765.15	$765.10