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	$201.39	11.540%	$224.6304	$224.63	$224.65	$224.60
Purchase #2	$66.93	9.403%	$73.2234	$73.22	$73.20	$73.20
Purchase #3	$243.98	6.453%	$259.724	$259.72	$259.70	$259.70
Purchase #4	$87.46	4.549%	$91.4386	$91.44	$91.45	$91.40
Purchase #5	$168.94	11.584%	$188.51	$188.51	$188.50	$188.50
Purchase #6	$94.51	12.334%	$106.1669	$106.17	$106.15	$106.20
Purchase #7	$174.36	12.587%	$196.3067	$196.31	$196.30	$196.30
7 purchase totals =	$1,037.57		$1,140.0000	$1,140.00	$1,139.95	$1,139.90