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	$235.50	3.535%	$243.8249	$243.82	$243.80	$243.80
Purchase #2	$228.46	12.515%	$257.0518	$257.05	$257.05	$257.10
Purchase #3	$33.44	3.393%	$34.5746	$34.57	$34.55	$34.60
Purchase #4	$146.62	8.756%	$159.458	$159.46	$159.45	$159.50
Purchase #5	$233.47	6.164%	$247.8611	$247.86	$247.85	$247.90
Purchase #6	$51.97	10.272%	$57.3084	$57.31	$57.30	$57.30
Purchase #7	$182.44	7.723%	$196.5298	$196.53	$196.55	$196.50
7 purchase totals =	$1,111.90		$1,196.6086	$1,196.60	$1,196.55	$1,196.70