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	$72.60	8.196%	$78.5503	$78.55	$78.55	$78.60
Purchase #2	$220.94	7.572%	$237.6696	$237.67	$237.65	$237.70
Purchase #3	$71.64	6.764%	$76.4857	$76.49	$76.50	$76.50
Purchase #4	$98.89	3.147%	$102.0021	$102.00	$102.00	$102.00
Purchase #5	$172.60	10.139%	$190.0999	$190.10	$190.10	$190.10
Purchase #6	$114.47	9.408%	$125.2393	$125.24	$125.25	$125.20
Purchase #7	$184.67	11.738%	$206.3466	$206.35	$206.35	$206.30
7 purchase totals =	$935.81		$1,016.3935	$1,016.40	$1,016.40	$1,016.40