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	$88.69	8.779%	$96.4761	$96.48	$96.50	$96.50
Purchase #2	$98.89	12.652%	$111.4016	$111.40	$111.40	$111.40
Purchase #3	$116.28	4.462%	$121.4684	$121.47	$121.45	$121.50
Purchase #4	$100.74	6.658%	$107.4473	$107.45	$107.45	$107.40
Purchase #5	$152.82	9.523%	$167.373	$167.37	$167.35	$167.40
Purchase #6	$136.98	10.212%	$150.9684	$150.97	$150.95	$151.00
Purchase #7	$245.98	9.664%	$269.7515	$269.75	$269.75	$269.80
7 purchase totals =	$940.38		$1,024.8863	$1,024.89	$1,024.85	$1,025.00