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	$185.71	4.716%	$194.4681	$194.47	$194.45	$194.50
Purchase #2	$248.52	11.107%	$276.1231	$276.12	$276.10	$276.10
Purchase #3	$191.81	4.351%	$200.1557	$200.16	$200.15	$200.20
Purchase #4	$237.45	5.436%	$250.3578	$250.36	$250.35	$250.40
Purchase #5	$45.89	11.159%	$51.0109	$51.01	$51.00	$51.00
Purchase #6	$124.56	11.301%	$138.6365	$138.64	$138.65	$138.60
Purchase #7	$12.31	11.188%	$13.6872	$13.69	$13.70	$13.70
7 purchase totals =	$1,046.25		$1,124.4393	$1,124.45	$1,124.40	$1,124.50