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	$190.86	7.448%	$205.0753	$205.08	$205.10	$205.10
Purchase #2	$204.60	8.727%	$222.4554	$222.46	$222.45	$222.50
Purchase #3	$113.85	8.826%	$123.8984	$123.90	$123.90	$123.90
Purchase #4	$88.34	9.747%	$96.9505	$96.95	$96.95	$97.00
Purchase #5	$166.41	8.452%	$180.475	$180.48	$180.50	$180.50
Purchase #6	$46.59	10.143%	$51.3156	$51.32	$51.30	$51.30
Purchase #7	$220.60	12.599%	$248.3934	$248.39	$248.40	$248.40
7 purchase totals =	$1,031.25		$1,128.5636	$1,128.58	$1,128.60	$1,128.70