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	$39.52	10.381%	$43.6226	$43.62	$43.60	$43.60
Purchase #2	$153.65	10.299%	$169.4744	$169.47	$169.45	$169.50
Purchase #3	$36.35	4.317%	$37.9192	$37.92	$37.90	$37.90
Purchase #4	$62.74	13.179%	$71.0085	$71.01	$71.00	$71.00
Purchase #5	$149.36	3.324%	$154.3247	$154.32	$154.30	$154.30
Purchase #6	$77.38	5.521%	$81.6521	$81.65	$81.65	$81.70
Purchase #7	$134.80	9.500%	$147.606	$147.61	$147.60	$147.60
7 purchase totals =	$653.80		$705.6075	$705.60	$705.50	$705.60