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	$57.46	7.564%	$61.8063	$61.81	$61.80	$61.80
Purchase #2	$190.74	12.396%	$214.3841	$214.38	$214.40	$214.40
Purchase #3	$46.93	11.222%	$52.1965	$52.20	$52.20	$52.20
Purchase #4	$205.72	9.669%	$225.6111	$225.61	$225.60	$225.60
Purchase #5	$172.89	3.618%	$179.1452	$179.15	$179.15	$179.10
Purchase #6	$240.59	12.851%	$271.5082	$271.51	$271.50	$271.50
Purchase #7	$147.93	9.769%	$162.3813	$162.38	$162.40	$162.40
7 purchase totals =	$1,062.26		$1,167.0327	$1,167.04	$1,167.05	$1,167.00