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	$142.47	6.752%	$152.0896	$152.09	$152.10	$152.10
Purchase #2	$197.75	12.383%	$222.2374	$222.24	$222.25	$222.20
Purchase #3	$50.50	13.602%	$57.369	$57.37	$57.35	$57.40
Purchase #4	$20.51	3.535%	$21.235	$21.24	$21.25	$21.20
Purchase #5	$98.33	6.334%	$104.5582	$104.56	$104.55	$104.60
Purchase #6	$85.50	4.456%	$89.3099	$89.31	$89.30	$89.30
Purchase #7	$64.53	7.742%	$69.5259	$69.53	$69.55	$69.50
7 purchase totals =	$659.59		$716.3250	$716.34	$716.35	$716.30