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	$91.98	4.618%	$96.2276	$96.23	$96.25	$96.20
Purchase #2	$238.33	7.630%	$256.5146	$256.51	$256.50	$256.50
Purchase #3	$85.86	6.798%	$91.6968	$91.70	$91.70	$91.70
Purchase #4	$214.48	8.800%	$233.3542	$233.35	$233.35	$233.40
Purchase #5	$101.90	10.357%	$112.4538	$112.45	$112.45	$112.50
Purchase #6	$113.47	11.630%	$126.6666	$126.67	$126.65	$126.70
Purchase #7	$178.90	3.440%	$185.0542	$185.05	$185.05	$185.10
7 purchase totals =	$1,024.92		$1,101.9678	$1,101.96	$1,101.95	$1,102.10