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	$199.88	3.591%	$207.0577	$207.06	$207.05	$207.10
Purchase #2	$139.89	5.534%	$147.6315	$147.63	$147.65	$147.60
Purchase #3	$52.31	3.508%	$54.145	$54.15	$54.15	$54.10
Purchase #4	$248.94	3.866%	$258.564	$258.56	$258.55	$258.60
Purchase #5	$88.26	3.780%	$91.5962	$91.60	$91.60	$91.60
Purchase #6	$106.38	10.839%	$117.9105	$117.91	$117.90	$117.90
Purchase #7	$50.56	11.851%	$56.5519	$56.55	$56.55	$56.60
7 purchase totals =	$886.22		$933.4568	$933.46	$933.45	$933.50