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	$114.38	4.446%	$119.4653	$119.47	$119.45	$119.50
Purchase #2	$153.47	7.483%	$164.9542	$164.95	$164.95	$165.00
Purchase #3	$72.59	9.704%	$79.6341	$79.63	$79.65	$79.60
Purchase #4	$173.85	10.140%	$191.4784	$191.48	$191.50	$191.50
Purchase #5	$155.45	10.708%	$172.0956	$172.10	$172.10	$172.10
Purchase #6	$176.83	11.316%	$196.8401	$196.84	$196.85	$196.80
Purchase #7	$199.95	3.398%	$206.7443	$206.74	$206.75	$206.70
7 purchase totals =	$1,046.52		$1,131.2120	$1,131.21	$1,131.25	$1,131.20