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	$158.50	9.757%	$173.9648	$173.96	$173.95	$174.00
Purchase #2	$208.80	3.278%	$215.6445	$215.64	$215.65	$215.60
Purchase #3	$83.45	10.838%	$92.4943	$92.49	$92.50	$92.50
Purchase #4	$41.26	10.459%	$45.5754	$45.58	$45.60	$45.60
Purchase #5	$130.31	5.410%	$137.3598	$137.36	$137.35	$137.40
Purchase #6	$76.53	3.737%	$79.3899	$79.39	$79.40	$79.40
Purchase #7	$140.85	6.837%	$150.4799	$150.48	$150.50	$150.50
7 purchase totals =	$839.70		$894.9086	$894.90	$894.95	$895.00