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	$179.86	6.717%	$191.9412	$191.94	$191.95	$191.90
Purchase #2	$119.62	3.405%	$123.6931	$123.69	$123.70	$123.70
Purchase #3	$177.40	11.686%	$198.131	$198.13	$198.15	$198.10
Purchase #4	$59.59	10.667%	$65.9465	$65.95	$65.95	$65.90
Purchase #5	$248.77	5.400%	$262.2036	$262.20	$262.20	$262.20
Purchase #6	$205.65	5.362%	$216.677	$216.68	$216.70	$216.70
Purchase #7	$74.86	11.627%	$83.564	$83.56	$83.55	$83.60
7 purchase totals =	$1,065.75		$1,142.1564	$1,142.15	$1,142.20	$1,142.10