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	$191.33	3.523%	$198.0706	$198.07	$198.05	$198.10
Purchase #2	$92.28	12.588%	$103.8962	$103.90	$103.90	$103.90
Purchase #3	$20.63	3.629%	$21.3787	$21.38	$21.40	$21.40
Purchase #4	$88.30	10.671%	$97.7225	$97.72	$97.70	$97.70
Purchase #5	$202.97	3.272%	$209.6112	$209.61	$209.60	$209.60
Purchase #6	$226.28	6.721%	$241.4883	$241.49	$241.50	$241.50
Purchase #7	$143.64	4.656%	$150.3279	$150.33	$150.35	$150.30
7 purchase totals =	$965.43		$1,022.4954	$1,022.50	$1,022.50	$1,022.50