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	$118.43	13.192%	$134.0533	$134.05	$134.05	$134.10
Purchase #2	$182.61	7.607%	$196.5011	$196.50	$196.50	$196.50
Purchase #3	$197.97	7.107%	$212.0397	$212.04	$212.05	$212.00
Purchase #4	$156.33	7.519%	$168.0845	$168.08	$168.10	$168.10
Purchase #5	$198.70	13.201%	$224.9304	$224.93	$224.95	$224.90
Purchase #6	$98.37	13.738%	$111.8841	$111.88	$111.90	$111.90
Purchase #7	$180.66	5.535%	$190.6595	$190.66	$190.65	$190.70
7 purchase totals =	$1,133.07		$1,238.1526	$1,238.14	$1,238.20	$1,238.20