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	$153.89	11.538%	$171.6458	$171.65	$171.65	$171.60
Purchase #2	$159.30	5.553%	$168.1459	$168.15	$168.15	$168.10
Purchase #3	$71.47	10.443%	$78.9336	$78.93	$78.95	$78.90
Purchase #4	$125.44	13.658%	$142.5726	$142.57	$142.55	$142.60
Purchase #5	$52.74	13.473%	$59.8457	$59.85	$59.85	$59.80
Purchase #6	$182.58	9.506%	$199.9361	$199.94	$199.95	$199.90
Purchase #7	$170.45	11.529%	$190.1012	$190.10	$190.10	$190.10
7 purchase totals =	$915.87		$1,011.1809	$1,011.19	$1,011.20	$1,011.00