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	$150.62	12.236%	$169.0499	$169.05	$169.05	$169.00
Purchase #2	$157.57	7.237%	$168.9733	$168.97	$168.95	$169.00
Purchase #3	$133.25	7.520%	$143.2704	$143.27	$143.25	$143.30
Purchase #4	$221.45	7.818%	$238.763	$238.76	$238.75	$238.80
Purchase #5	$18.60	11.842%	$20.8026	$20.80	$20.80	$20.80
Purchase #6	$51.71	5.446%	$54.5261	$54.53	$54.55	$54.50
Purchase #7	$243.35	6.671%	$259.5839	$259.58	$259.60	$259.60
7 purchase totals =	$976.55		$1,054.9692	$1,054.96	$1,054.95	$1,055.00