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	$181.98	10.711%	$201.4719	$201.47	$201.45	$201.50
Purchase #2	$59.78	3.758%	$62.0265	$62.03	$62.05	$62.00
Purchase #3	$156.78	11.289%	$174.4789	$174.48	$174.50	$174.50
Purchase #4	$181.83	9.835%	$199.713	$199.71	$199.70	$199.70
Purchase #5	$81.67	10.267%	$90.0551	$90.06	$90.05	$90.10
Purchase #6	$11.80	12.293%	$13.2506	$13.25	$13.25	$13.30
Purchase #7	$175.67	5.514%	$185.3564	$185.36	$185.35	$185.40
7 purchase totals =	$849.51		$926.3524	$926.36	$926.35	$926.50