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	$10.61	6.748%	$11.326	$11.33	$11.35	$11.30
Purchase #2	$46.78	4.215%	$48.7518	$48.75	$48.75	$48.80
Purchase #3	$15.27	6.577%	$16.2743	$16.27	$16.25	$16.30
Purchase #4	$12.25	10.810%	$13.5742	$13.57	$13.55	$13.60
Purchase #5	$16.86	7.825%	$18.1793	$18.18	$18.20	$18.20
Purchase #6	$105.37	4.183%	$109.7776	$109.78	$109.80	$109.80
Purchase #7	$156.29	6.758%	$166.8521	$166.85	$166.85	$166.90
7 purchase totals =	$363.43		$384.7353	$384.73	$384.75	$384.90