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	$188.86	4.297%	$196.9753	$196.98	$197.00	$197.00
Purchase #2	$194.43	9.275%	$212.4634	$212.46	$212.45	$212.50
Purchase #3	$59.70	5.401%	$62.9244	$62.92	$62.90	$62.90
Purchase #4	$111.76	3.540%	$115.7163	$115.72	$115.70	$115.70
Purchase #5	$100.81	4.588%	$105.4352	$105.44	$105.45	$105.40
Purchase #6	$160.31	12.729%	$180.7159	$180.72	$180.70	$180.70
Purchase #7	$224.76	10.712%	$248.8363	$248.84	$248.85	$248.80
7 purchase totals =	$1,040.63		$1,123.0668	$1,123.08	$1,123.05	$1,123.00