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	$62.62	4.705%	$65.5663	$65.57	$65.55	$65.60
Purchase #2	$196.73	10.553%	$217.4909	$217.49	$217.50	$217.50
Purchase #3	$238.84	11.199%	$265.5877	$265.59	$265.60	$265.60
Purchase #4	$79.64	4.223%	$83.0032	$83.00	$83.00	$83.00
Purchase #5	$55.99	6.238%	$59.4827	$59.48	$59.50	$59.50
Purchase #6	$192.90	5.651%	$203.8008	$203.80	$203.80	$203.80
Purchase #7	$231.45	12.113%	$259.4855	$259.49	$259.50	$259.50
7 purchase totals =	$1,058.17		$1,154.4171	$1,154.42	$1,154.45	$1,154.50