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	$208.85	3.649%	$216.4709	$216.47	$216.45	$216.50
Purchase #2	$97.45	8.349%	$105.5861	$105.59	$105.60	$105.60
Purchase #3	$241.95	4.814%	$253.5975	$253.60	$253.60	$253.60
Purchase #4	$67.93	8.274%	$73.5505	$73.55	$73.55	$73.60
Purchase #5	$88.57	10.127%	$97.5395	$97.54	$97.55	$97.50
Purchase #6	$95.53	7.420%	$102.6183	$102.62	$102.60	$102.60
Purchase #7	$240.75	9.705%	$264.1148	$264.11	$264.10	$264.10
7 purchase totals =	$1,041.03		$1,113.4776	$1,113.48	$1,113.45	$1,113.50