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	$73.70	12.337%	$82.7924	$82.79	$82.80	$82.80
Purchase #2	$9.79	5.591%	$10.3374	$10.34	$10.35	$10.30
Purchase #3	$36.39	4.659%	$38.0854	$38.09	$38.10	$38.10
Purchase #4	$109.85	12.729%	$123.8328	$123.83	$123.85	$123.80
Purchase #5	$98.33	4.650%	$102.9023	$102.90	$102.90	$102.90
Purchase #6	$119.43	4.711%	$125.0563	$125.06	$125.05	$125.10
Purchase #7	$243.43	10.727%	$269.5427	$269.54	$269.55	$269.50
7 purchase totals =	$690.92		$752.5493	$752.55	$752.60	$752.50