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	$124.85	10.291%	$137.6983	$137.70	$137.70	$137.70
Purchase #2	$95.96	5.743%	$101.471	$101.47	$101.45	$101.50
Purchase #3	$111.25	12.131%	$124.7457	$124.75	$124.75	$124.70
Purchase #4	$162.82	11.453%	$181.4678	$181.47	$181.45	$181.50
Purchase #5	$166.74	6.696%	$177.9049	$177.90	$177.90	$177.90
Purchase #6	$127.51	5.453%	$134.4631	$134.46	$134.45	$134.50
Purchase #7	$152.89	9.620%	$167.598	$167.60	$167.60	$167.60
7 purchase totals =	$942.02		$1,025.3488	$1,025.35	$1,025.30	$1,025.40