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	$211.27	5.528%	$222.949	$222.95	$222.95	$222.90
Purchase #2	$208.50	7.672%	$224.4961	$224.50	$224.50	$224.50
Purchase #3	$77.54	6.800%	$82.8127	$82.81	$82.80	$82.80
Purchase #4	$61.97	3.648%	$64.2307	$64.23	$64.25	$64.20
Purchase #5	$119.43	10.496%	$131.9654	$131.97	$131.95	$132.00
Purchase #6	$96.32	4.725%	$100.8711	$100.87	$100.85	$100.90
Purchase #7	$247.57	10.427%	$273.3841	$273.38	$273.40	$273.40
7 purchase totals =	$1,022.60		$1,100.7091	$1,100.71	$1,100.70	$1,100.70