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	$63.67	5.234%	$67.0025	$67.00	$67.00	$67.00
Purchase #2	$229.26	8.391%	$248.4972	$248.50	$248.50	$248.50
Purchase #3	$168.85	9.498%	$184.8874	$184.89	$184.90	$184.90
Purchase #4	$142.33	5.427%	$150.0542	$150.05	$150.05	$150.10
Purchase #5	$99.72	13.282%	$112.9648	$112.96	$112.95	$113.00
Purchase #6	$128.86	3.347%	$133.1729	$133.17	$133.15	$133.20
Purchase #7	$139.29	13.394%	$157.9465	$157.95	$157.95	$157.90
7 purchase totals =	$971.98		$1,054.5255	$1,054.52	$1,054.50	$1,054.60