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	$190.94	9.662%	$209.3886	$209.39	$209.40	$209.40
Purchase #2	$128.51	5.233%	$135.2349	$135.23	$135.25	$135.20
Purchase #3	$54.38	9.289%	$59.4314	$59.43	$59.45	$59.40
Purchase #4	$234.76	12.517%	$264.1449	$264.14	$264.15	$264.10
Purchase #5	$55.50	12.395%	$62.3792	$62.38	$62.40	$62.40
Purchase #6	$24.28	4.201%	$25.3	$25.30	$25.30	$25.30
Purchase #7	$237.64	12.117%	$266.4348	$266.43	$266.45	$266.40
7 purchase totals =	$926.01		$1,022.3138	$1,022.30	$1,022.40	$1,022.20