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	$140.60	3.180%	$145.0711	$145.07	$145.05	$145.10
Purchase #2	$39.80	5.727%	$42.0793	$42.08	$42.10	$42.10
Purchase #3	$29.54	13.455%	$33.5146	$33.51	$33.50	$33.50
Purchase #4	$8.93	12.665%	$10.061	$10.06	$10.05	$10.10
Purchase #5	$7.83	3.172%	$8.0784	$8.08	$8.10	$8.10
Purchase #6	$12.32	4.468%	$12.8705	$12.87	$12.85	$12.90
Purchase #7	$113.90	4.346%	$118.8501	$118.85	$118.85	$118.90
7 purchase totals =	$352.92		$370.5250	$370.52	$370.50	$370.70