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	$86.25	12.573%	$97.0942	$97.09	$97.10	$97.10
Purchase #2	$143.63	6.300%	$152.6787	$152.68	$152.70	$152.70
Purchase #3	$122.64	11.739%	$137.0367	$137.04	$137.05	$137.00
Purchase #4	$187.30	7.228%	$200.838	$200.84	$200.85	$200.80
Purchase #5	$145.33	7.849%	$156.737	$156.74	$156.75	$156.70
Purchase #6	$107.49	3.508%	$111.2607	$111.26	$111.25	$111.30
Purchase #7	$148.43	5.410%	$156.4601	$156.46	$156.45	$156.50
7 purchase totals =	$941.07		$1,012.1054	$1,012.11	$1,012.15	$1,012.10