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	$191.59	13.417%	$217.2956	$217.30	$217.30	$217.30
Purchase #2	$158.95	3.429%	$164.4004	$164.40	$164.40	$164.40
Purchase #3	$13.55	7.808%	$14.608	$14.61	$14.60	$14.60
Purchase #4	$42.52	6.623%	$45.3361	$45.34	$45.35	$45.30
Purchase #5	$154.43	6.703%	$164.7814	$164.78	$164.80	$164.80
Purchase #6	$6.76	7.144%	$7.2429	$7.24	$7.25	$7.20
Purchase #7	$66.32	11.802%	$74.1471	$74.15	$74.15	$74.10
7 purchase totals =	$634.12		$687.8115	$687.82	$687.85	$687.70