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	$146.55	3.661%	$151.9152	$151.92	$151.90	$151.90
Purchase #2	$199.72	8.438%	$216.5724	$216.57	$216.55	$216.60
Purchase #3	$206.36	6.360%	$219.4845	$219.48	$219.50	$219.50
Purchase #4	$19.79	10.448%	$21.8577	$21.86	$21.85	$21.90
Purchase #5	$240.78	12.516%	$270.916	$270.92	$270.90	$270.90
Purchase #6	$46.66	13.780%	$53.0897	$53.09	$53.10	$53.10
Purchase #7	$74.47	8.164%	$80.5497	$80.55	$80.55	$80.50
7 purchase totals =	$934.33		$1,014.3852	$1,014.39	$1,014.35	$1,014.40