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	$226.93	6.448%	$241.5624	$241.56	$241.55	$241.60
Purchase #2	$186.58	4.601%	$195.1645	$195.16	$195.15	$195.20
Purchase #3	$9.26	13.761%	$10.5343	$10.53	$10.55	$10.50
Purchase #4	$78.46	13.831%	$89.3118	$89.31	$89.30	$89.30
Purchase #5	$92.68	10.243%	$102.1732	$102.17	$102.15	$102.20
Purchase #6	$226.78	8.291%	$245.5823	$245.58	$245.60	$245.60
Purchase #7	$104.32	12.397%	$117.2526	$117.25	$117.25	$117.30
7 purchase totals =	$925.01		$1,001.5811	$1,001.56	$1,001.55	$1,001.70