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	$85.31	11.432%	$95.0626	$95.06	$95.05	$95.10
Purchase #2	$163.26	3.199%	$168.4827	$168.48	$168.50	$168.50
Purchase #3	$29.63	8.504%	$32.1497	$32.15	$32.15	$32.10
Purchase #4	$103.56	12.556%	$116.563	$116.56	$116.55	$116.60
Purchase #5	$223.53	7.717%	$240.7798	$240.78	$240.80	$240.80
Purchase #6	$37.87	13.348%	$42.9249	$42.92	$42.90	$42.90
Purchase #7	$188.53	7.130%	$201.9722	$201.97	$201.95	$202.00
7 purchase totals =	$831.69		$897.9349	$897.92	$897.90	$898.00