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	$119.84	10.620%	$132.567	$132.57	$132.55	$132.60
Purchase #2	$38.70	5.572%	$40.8564	$40.86	$40.85	$40.90
Purchase #3	$244.40	10.699%	$270.5484	$270.55	$270.55	$270.50
Purchase #4	$13.96	12.653%	$15.7264	$15.73	$15.75	$15.70
Purchase #5	$26.65	13.691%	$30.2987	$30.30	$30.30	$30.30
Purchase #6	$238.47	7.671%	$256.763	$256.76	$256.75	$256.80
Purchase #7	$246.54	10.135%	$271.5268	$271.53	$271.55	$271.50
7 purchase totals =	$928.56		$1,018.2867	$1,018.30	$1,018.30	$1,018.30