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	$81.93	4.445%	$85.5718	$85.57	$85.55	$85.60
Purchase #2	$62.53	8.592%	$67.9026	$67.90	$67.90	$67.90
Purchase #3	$185.60	12.103%	$208.0632	$208.06	$208.05	$208.10
Purchase #4	$184.53	5.464%	$194.6127	$194.61	$194.60	$194.60
Purchase #5	$23.81	6.182%	$25.2819	$25.28	$25.30	$25.30
Purchase #6	$238.94	12.681%	$269.24	$269.24	$269.25	$269.20
Purchase #7	$97.68	6.321%	$103.8544	$103.85	$103.85	$103.90
7 purchase totals =	$875.02		$954.5266	$954.51	$954.50	$954.60