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	$195.80	7.566%	$210.6142	$210.61	$210.60	$210.60
Purchase #2	$104.53	12.355%	$117.4447	$117.44	$117.45	$117.40
Purchase #3	$187.68	4.628%	$196.3658	$196.37	$196.35	$196.40
Purchase #4	$167.34	4.340%	$174.6026	$174.60	$174.60	$174.60
Purchase #5	$63.60	7.736%	$68.5201	$68.52	$68.50	$68.50
Purchase #6	$113.25	12.421%	$127.3168	$127.32	$127.30	$127.30
Purchase #7	$50.50	9.495%	$55.295	$55.30	$55.30	$55.30
7 purchase totals =	$882.70		$950.1592	$950.16	$950.10	$950.10