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	$178.48	10.210%	$196.7028	$196.70	$196.70	$196.70
Purchase #2	$85.36	11.532%	$95.2037	$95.20	$95.20	$95.20
Purchase #3	$170.83	9.215%	$186.572	$186.57	$186.55	$186.60
Purchase #4	$194.47	9.528%	$212.9991	$213.00	$213.00	$213.00
Purchase #5	$23.30	11.282%	$25.9287	$25.93	$25.95	$25.90
Purchase #6	$182.56	7.462%	$196.1826	$196.18	$196.20	$196.20
Purchase #7	$171.32	6.518%	$182.4866	$182.49	$182.50	$182.50
7 purchase totals =	$1,006.32		$1,096.0755	$1,096.07	$1,096.10	$1,096.10