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	$133.85	10.143%	$147.4264	$147.43	$147.45	$147.40
Purchase #2	$250.34	7.612%	$269.3959	$269.40	$269.40	$269.40
Purchase #3	$137.62	9.291%	$150.4063	$150.41	$150.40	$150.40
Purchase #4	$62.51	8.469%	$67.804	$67.80	$67.80	$67.80
Purchase #5	$13.82	5.697%	$14.6073	$14.61	$14.60	$14.60
Purchase #6	$213.87	4.846%	$224.2341	$224.23	$224.25	$224.20
Purchase #7	$130.54	8.844%	$142.085	$142.09	$142.10	$142.10
7 purchase totals =	$942.55		$1,015.9590	$1,015.97	$1,016.00	$1,015.90