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	$82.55	13.571%	$93.7529	$93.75	$93.75	$93.80
Purchase #2	$49.65	3.830%	$51.5516	$51.55	$51.55	$51.60
Purchase #3	$23.30	6.164%	$24.7362	$24.74	$24.75	$24.70
Purchase #4	$73.69	6.652%	$78.5919	$78.59	$78.60	$78.60
Purchase #5	$11.49	10.699%	$12.7193	$12.72	$12.70	$12.70
Purchase #6	$122.89	11.186%	$136.6365	$136.64	$136.65	$136.60
Purchase #7	$69.82	3.461%	$72.2365	$72.24	$72.25	$72.20
7 purchase totals =	$433.39		$470.2249	$470.23	$470.25	$470.20