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	$233.68	3.747%	$242.436	$242.44	$242.45	$242.40
Purchase #2	$20.88	12.335%	$23.4555	$23.46	$23.45	$23.50
Purchase #3	$207.63	5.579%	$219.2137	$219.21	$219.20	$219.20
Purchase #4	$85.80	4.472%	$89.637	$89.64	$89.65	$89.60
Purchase #5	$223.84	4.342%	$233.5591	$233.56	$233.55	$233.60
Purchase #6	$225.52	6.538%	$240.2645	$240.26	$240.25	$240.30
Purchase #7	$86.77	7.723%	$93.4712	$93.47	$93.45	$93.50
7 purchase totals =	$1,084.12		$1,142.0370	$1,142.04	$1,142.00	$1,142.10