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	$91.89	5.278%	$96.74	$96.74	$96.75	$96.70
Purchase #2	$190.60	7.869%	$205.5983	$205.60	$205.60	$205.60
Purchase #3	$58.45	13.555%	$66.3729	$66.37	$66.35	$66.40
Purchase #4	$159.93	12.791%	$180.3866	$180.39	$180.40	$180.40
Purchase #5	$43.56	4.849%	$45.6722	$45.67	$45.65	$45.70
Purchase #6	$205.83	5.789%	$217.7455	$217.75	$217.75	$217.70
Purchase #7	$187.44	9.657%	$205.5411	$205.54	$205.55	$205.50
7 purchase totals =	$937.70		$1,018.0566	$1,018.06	$1,018.05	$1,018.00