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	$63.72	13.786%	$72.5044	$72.50	$72.50	$72.50
Purchase #2	$12.28	11.866%	$13.7371	$13.74	$13.75	$13.70
Purchase #3	$29.82	4.680%	$31.2156	$31.22	$31.20	$31.20
Purchase #4	$55.85	13.326%	$63.2926	$63.29	$63.30	$63.30
Purchase #5	$13.90	3.823%	$14.4314	$14.43	$14.45	$14.40
Purchase #6	$81.54	11.173%	$90.6505	$90.65	$90.65	$90.70
Purchase #7	$77.25	13.321%	$87.5405	$87.54	$87.55	$87.50
7 purchase totals =	$334.36		$373.3721	$373.37	$373.40	$373.30