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	$162.28	8.424%	$175.9505	$175.95	$175.95	$176.00
Purchase #2	$62.64	5.472%	$66.0677	$66.07	$66.05	$66.10
Purchase #3	$58.84	6.185%	$62.4793	$62.48	$62.50	$62.50
Purchase #4	$139.48	9.276%	$152.4182	$152.42	$152.40	$152.40
Purchase #5	$216.43	7.714%	$233.1254	$233.13	$233.15	$233.10
Purchase #6	$100.50	8.523%	$109.0656	$109.07	$109.05	$109.10
Purchase #7	$145.48	13.323%	$164.8623	$164.86	$164.85	$164.90
7 purchase totals =	$885.65		$963.9690	$963.98	$963.95	$964.10