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	$142.62	13.687%	$162.1404	$162.14	$162.15	$162.10
Purchase #2	$177.25	12.844%	$200.016	$200.02	$200.00	$200.00
Purchase #3	$109.38	6.153%	$116.1102	$116.11	$116.10	$116.10
Purchase #4	$169.38	9.771%	$185.9301	$185.93	$185.95	$185.90
Purchase #5	$137.91	4.609%	$144.2663	$144.27	$144.25	$144.30
Purchase #6	$217.97	5.625%	$230.2308	$230.23	$230.25	$230.20
Purchase #7	$195.93	6.609%	$208.879	$208.88	$208.90	$208.90
7 purchase totals =	$1,150.44		$1,247.5728	$1,247.58	$1,247.60	$1,247.50