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	$161.45	9.370%	$176.5779	$176.58	$176.60	$176.60
Purchase #2	$174.25	7.670%	$187.615	$187.62	$187.60	$187.60
Purchase #3	$158.32	6.509%	$168.625	$168.63	$168.65	$168.60
Purchase #4	$196.89	9.153%	$214.9113	$214.91	$214.90	$214.90
Purchase #5	$79.39	9.253%	$86.736	$86.74	$86.75	$86.70
Purchase #6	$64.46	11.470%	$71.8536	$71.85	$71.85	$71.90
Purchase #7	$137.77	6.771%	$147.0984	$147.10	$147.10	$147.10
7 purchase totals =	$972.53		$1,053.4172	$1,053.43	$1,053.45	$1,053.40