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	$174.69	12.195%	$195.9934	$195.99	$196.00	$196.00
Purchase #2	$120.79	9.703%	$132.5103	$132.51	$132.50	$132.50
Purchase #3	$161.55	3.273%	$166.8375	$166.84	$166.85	$166.80
Purchase #4	$116.42	3.190%	$120.1338	$120.13	$120.15	$120.10
Purchase #5	$132.72	9.555%	$145.4014	$145.40	$145.40	$145.40
Purchase #6	$203.77	5.814%	$215.6172	$215.62	$215.60	$215.60
Purchase #7	$102.94	6.794%	$109.9337	$109.93	$109.95	$109.90
7 purchase totals =	$1,012.88		$1,086.4273	$1,086.42	$1,086.45	$1,086.30