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	$59.34	5.480%	$62.5918	$62.59	$62.60	$62.60
Purchase #2	$150.80	11.469%	$168.0953	$168.10	$168.10	$168.10
Purchase #3	$187.92	7.707%	$202.403	$202.40	$202.40	$202.40
Purchase #4	$144.98	3.736%	$150.3965	$150.40	$150.40	$150.40
Purchase #5	$29.96	8.657%	$32.5536	$32.55	$32.55	$32.60
Purchase #6	$86.78	9.378%	$94.9182	$94.92	$94.90	$94.90
Purchase #7	$215.61	5.527%	$227.5268	$227.53	$227.55	$227.50
7 purchase totals =	$875.39		$938.4852	$938.49	$938.50	$938.50