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	$188.43	4.516%	$196.9395	$196.94	$196.95	$196.90
Purchase #2	$10.69	11.257%	$11.8934	$11.89	$11.90	$11.90
Purchase #3	$98.77	7.168%	$105.8498	$105.85	$105.85	$105.80
Purchase #4	$22.68	10.646%	$25.0945	$25.09	$25.10	$25.10
Purchase #5	$121.54	5.294%	$127.9743	$127.97	$127.95	$128.00
Purchase #6	$182.27	12.470%	$204.9991	$205.00	$205.00	$205.00
Purchase #7	$119.76	9.435%	$131.0594	$131.06	$131.05	$131.10
7 purchase totals =	$744.14		$803.8100	$803.80	$803.80	$803.80