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	$10.59	3.532%	$10.964	$10.96	$10.95	$11.00
Purchase #2	$89.51	12.697%	$100.8751	$100.88	$100.90	$100.90
Purchase #3	$182.29	11.232%	$202.7648	$202.76	$202.75	$202.80
Purchase #4	$162.37	5.398%	$171.1347	$171.13	$171.15	$171.10
Purchase #5	$179.50	10.493%	$198.3349	$198.33	$198.35	$198.30
Purchase #6	$71.52	9.559%	$78.3566	$78.36	$78.35	$78.40
Purchase #7	$228.65	13.774%	$260.1443	$260.14	$260.15	$260.10
7 purchase totals =	$924.43		$1,022.5744	$1,022.56	$1,022.60	$1,022.60