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	$211.40	5.249%	$222.4964	$222.50	$222.50	$222.50
Purchase #2	$241.25	10.731%	$267.1385	$267.14	$267.15	$267.10
Purchase #3	$72.31	5.233%	$76.094	$76.09	$76.10	$76.10
Purchase #4	$59.28	13.311%	$67.1708	$67.17	$67.15	$67.20
Purchase #5	$50.96	3.507%	$52.7472	$52.75	$52.75	$52.70
Purchase #6	$95.32	5.467%	$100.5311	$100.53	$100.55	$100.50
Purchase #7	$239.87	7.293%	$257.3637	$257.36	$257.35	$257.40
7 purchase totals =	$970.39		$1,043.5417	$1,043.54	$1,043.55	$1,043.50