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	$182.64	7.570%	$196.4658	$196.47	$196.45	$196.50
Purchase #2	$237.73	10.456%	$262.587	$262.59	$262.60	$262.60
Purchase #3	$148.29	8.353%	$160.6767	$160.68	$160.70	$160.70
Purchase #4	$104.99	4.726%	$109.9518	$109.95	$109.95	$110.00
Purchase #5	$65.84	9.366%	$72.0066	$72.01	$72.00	$72.00
Purchase #6	$49.92	9.359%	$54.592	$54.59	$54.60	$54.60
Purchase #7	$54.38	3.331%	$56.1914	$56.19	$56.20	$56.20
7 purchase totals =	$843.79		$912.4713	$912.48	$912.50	$912.60