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	$201.44	7.530%	$216.6084	$216.61	$216.60	$216.60
Purchase #2	$228.77	6.172%	$242.8897	$242.89	$242.90	$242.90
Purchase #3	$82.60	5.223%	$86.9142	$86.91	$86.90	$86.90
Purchase #4	$118.82	10.819%	$131.6751	$131.68	$131.70	$131.70
Purchase #5	$137.61	6.666%	$146.7831	$146.78	$146.80	$146.80
Purchase #6	$77.54	10.184%	$85.4367	$85.44	$85.45	$85.40
Purchase #7	$92.94	11.716%	$103.8289	$103.83	$103.85	$103.80
7 purchase totals =	$939.72		$1,014.1361	$1,014.14	$1,014.20	$1,014.10