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	$176.31	11.190%	$196.0391	$196.04	$196.05	$196.00
Purchase #2	$134.35	9.321%	$146.8728	$146.87	$146.85	$146.90
Purchase #3	$86.43	3.219%	$89.2122	$89.21	$89.20	$89.20
Purchase #4	$46.84	8.759%	$50.9427	$50.94	$50.95	$50.90
Purchase #5	$129.36	13.343%	$146.6205	$146.62	$146.60	$146.60
Purchase #6	$206.57	4.377%	$215.6116	$215.61	$215.60	$215.60
Purchase #7	$151.64	7.464%	$162.9584	$162.96	$162.95	$163.00
7 purchase totals =	$931.50		$1,008.2573	$1,008.25	$1,008.20	$1,008.20