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	$117.41	7.705%	$126.4564	$126.46	$126.45	$126.50
Purchase #2	$50.84	7.305%	$54.5539	$54.55	$54.55	$54.60
Purchase #3	$163.89	12.827%	$184.9122	$184.91	$184.90	$184.90
Purchase #4	$181.57	6.792%	$193.9022	$193.90	$193.90	$193.90
Purchase #5	$65.86	11.672%	$73.5472	$73.55	$73.55	$73.50
Purchase #6	$169.36	12.320%	$190.2252	$190.23	$190.25	$190.20
Purchase #7	$127.71	11.510%	$142.4094	$142.41	$142.40	$142.40
7 purchase totals =	$876.64		$966.0065	$966.01	$966.00	$966.00