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	$201.52	5.178%	$211.9547	$211.95	$211.95	$212.00
Purchase #2	$135.89	11.682%	$151.7647	$151.76	$151.75	$151.80
Purchase #3	$196.49	9.556%	$215.2666	$215.27	$215.25	$215.30
Purchase #4	$43.56	11.420%	$48.5346	$48.53	$48.55	$48.50
Purchase #5	$89.59	11.708%	$100.0792	$100.08	$100.10	$100.10
Purchase #6	$206.88	9.250%	$226.0164	$226.02	$226.00	$226.00
Purchase #7	$133.32	13.698%	$151.5822	$151.58	$151.60	$151.60
7 purchase totals =	$1,007.25		$1,105.1984	$1,105.19	$1,105.20	$1,105.30