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	$45.98	7.302%	$49.3375	$49.34	$49.35	$49.30
Purchase #2	$177.54	8.271%	$192.2243	$192.22	$192.20	$192.20
Purchase #3	$173.54	7.124%	$185.903	$185.90	$185.90	$185.90
Purchase #4	$180.32	6.423%	$191.902	$191.90	$191.90	$191.90
Purchase #5	$248.31	3.276%	$256.4446	$256.44	$256.45	$256.40
Purchase #6	$131.37	7.789%	$141.6024	$141.60	$141.60	$141.60
Purchase #7	$179.87	10.565%	$198.8733	$198.87	$198.85	$198.90
7 purchase totals =	$1,136.93		$1,216.2871	$1,216.27	$1,216.25	$1,216.20