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	$112.83	11.401%	$125.6937	$125.69	$125.70	$125.70
Purchase #2	$155.42	5.681%	$164.2494	$164.25	$164.25	$164.20
Purchase #3	$139.50	9.473%	$152.7148	$152.71	$152.70	$152.70
Purchase #4	$242.73	9.534%	$265.8719	$265.87	$265.85	$265.90
Purchase #5	$123.30	11.701%	$137.7273	$137.73	$137.75	$137.70
Purchase #6	$233.48	11.216%	$259.6671	$259.67	$259.65	$259.70
Purchase #7	$41.76	12.279%	$46.8877	$46.89	$46.90	$46.90
7 purchase totals =	$1,049.02		$1,152.8119	$1,152.81	$1,152.80	$1,152.80