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	$89.68	6.494%	$95.5038	$95.50	$95.50	$95.50
Purchase #2	$184.30	6.575%	$196.4177	$196.42	$196.40	$196.40
Purchase #3	$201.29	9.117%	$219.6416	$219.64	$219.65	$219.60
Purchase #4	$240.63	3.291%	$248.5491	$248.55	$248.55	$248.50
Purchase #5	$174.85	6.278%	$185.8271	$185.83	$185.85	$185.80
Purchase #6	$167.89	5.236%	$176.6807	$176.68	$176.70	$176.70
Purchase #7	$161.33	9.642%	$176.8854	$176.89	$176.90	$176.90
7 purchase totals =	$1,219.97		$1,299.5054	$1,299.51	$1,299.55	$1,299.40