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	$175.67	8.445%	$190.5053	$190.51	$190.50	$190.50
Purchase #2	$66.69	8.842%	$72.5867	$72.59	$72.60	$72.60
Purchase #3	$54.57	13.444%	$61.9064	$61.91	$61.90	$61.90
Purchase #4	$141.82	4.789%	$148.6118	$148.61	$148.60	$148.60
Purchase #5	$180.71	12.532%	$203.3566	$203.36	$203.35	$203.40
Purchase #6	$62.95	10.475%	$69.544	$69.54	$69.55	$69.50
Purchase #7	$11.42	3.249%	$11.791	$11.79	$11.80	$11.80
7 purchase totals =	$693.83		$758.3018	$758.31	$758.30	$758.30