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	$222.81	10.389%	$245.9577	$245.96	$245.95	$246.00
Purchase #2	$10.61	11.288%	$11.8077	$11.81	$11.80	$11.80
Purchase #3	$43.46	6.520%	$46.2936	$46.29	$46.30	$46.30
Purchase #4	$238.31	3.399%	$246.4102	$246.41	$246.40	$246.40
Purchase #5	$56.76	9.293%	$62.0347	$62.03	$62.05	$62.00
Purchase #6	$38.69	9.512%	$42.3702	$42.37	$42.35	$42.40
Purchase #7	$96.53	6.761%	$103.0564	$103.06	$103.05	$103.10
7 purchase totals =	$707.17		$757.9305	$757.93	$757.90	$758.00