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	$119.30	6.472%	$127.0211	$127.02	$127.00	$127.00
Purchase #2	$11.37	9.541%	$12.4548	$12.45	$12.45	$12.50
Purchase #3	$244.51	4.732%	$256.0802	$256.08	$256.10	$256.10
Purchase #4	$165.32	7.387%	$177.5322	$177.53	$177.55	$177.50
Purchase #5	$79.61	9.714%	$87.3433	$87.34	$87.35	$87.30
Purchase #6	$111.42	11.667%	$124.4194	$124.42	$124.40	$124.40
Purchase #7	$218.57	9.123%	$238.5101	$238.51	$238.50	$238.50
7 purchase totals =	$950.10		$1,023.3611	$1,023.35	$1,023.35	$1,023.30