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	$179.37	9.583%	$196.559	$196.56	$196.55	$196.60
Purchase #2	$32.52	12.293%	$36.5177	$36.52	$36.50	$36.50
Purchase #3	$80.72	6.402%	$85.8877	$85.89	$85.90	$85.90
Purchase #4	$219.43	9.833%	$241.0066	$241.01	$241.00	$241.00
Purchase #5	$210.89	10.413%	$232.85	$232.85	$232.85	$232.90
Purchase #6	$184.99	5.146%	$194.5096	$194.51	$194.50	$194.50
Purchase #7	$231.86	6.817%	$247.6659	$247.67	$247.65	$247.70
7 purchase totals =	$1,139.78		$1,234.9965	$1,235.01	$1,234.95	$1,235.10