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	$196.86	10.478%	$217.487	$217.49	$217.50	$217.50
Purchase #2	$19.27	6.231%	$20.4707	$20.47	$20.45	$20.50
Purchase #3	$221.87	8.703%	$241.1793	$241.18	$241.20	$241.20
Purchase #4	$223.94	5.219%	$235.6274	$235.63	$235.65	$235.60
Purchase #5	$33.96	12.563%	$38.2264	$38.23	$38.25	$38.20
Purchase #6	$82.55	9.753%	$90.6011	$90.60	$90.60	$90.60
Purchase #7	$182.91	12.820%	$206.3591	$206.36	$206.35	$206.40
7 purchase totals =	$961.36		$1,049.9510	$1,049.96	$1,050.00	$1,050.00