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	$107.66	6.460%	$114.6148	$114.61	$114.60	$114.60
Purchase #2	$9.32	5.452%	$9.8281	$9.83	$9.85	$9.80
Purchase #3	$70.30	12.228%	$78.8963	$78.90	$78.90	$78.90
Purchase #4	$168.76	12.537%	$189.9174	$189.92	$189.90	$189.90
Purchase #5	$43.27	5.808%	$45.7831	$45.78	$45.80	$45.80
Purchase #6	$226.68	6.553%	$241.5343	$241.53	$241.55	$241.50
Purchase #7	$185.31	10.168%	$204.1523	$204.15	$204.15	$204.20
7 purchase totals =	$811.30		$884.7263	$884.72	$884.75	$884.70