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	$227.92	6.768%	$243.3456	$243.35	$243.35	$243.30
Purchase #2	$142.62	5.628%	$150.6467	$150.65	$150.65	$150.60
Purchase #3	$196.33	6.160%	$208.4239	$208.42	$208.40	$208.40
Purchase #4	$14.92	4.194%	$15.5457	$15.55	$15.55	$15.50
Purchase #5	$154.67	5.348%	$162.9418	$162.94	$162.95	$162.90
Purchase #6	$19.65	6.564%	$20.9398	$20.94	$20.95	$20.90
Purchase #7	$203.38	9.832%	$223.3763	$223.38	$223.40	$223.40
7 purchase totals =	$959.49		$1,025.2198	$1,025.23	$1,025.25	$1,025.00