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	$61.32	3.596%	$63.5251	$63.53	$63.55	$63.50
Purchase #2	$141.54	7.466%	$152.1074	$152.11	$152.10	$152.10
Purchase #3	$145.39	4.785%	$152.3469	$152.35	$152.35	$152.30
Purchase #4	$229.26	11.361%	$255.3062	$255.31	$255.30	$255.30
Purchase #5	$225.95	7.800%	$243.5741	$243.57	$243.55	$243.60
Purchase #6	$237.85	7.862%	$256.5498	$256.55	$256.55	$256.50
Purchase #7	$230.60	6.670%	$245.981	$245.98	$246.00	$246.00
7 purchase totals =	$1,271.91		$1,369.3905	$1,369.40	$1,369.40	$1,369.30