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	$149.33	10.265%	$164.6587	$164.66	$164.65	$164.70
Purchase #2	$94.70	6.575%	$100.9265	$100.93	$100.95	$100.90
Purchase #3	$5.87	10.432%	$6.4824	$6.48	$6.50	$6.50
Purchase #4	$235.26	6.545%	$250.6578	$250.66	$250.65	$250.70
Purchase #5	$152.91	8.727%	$166.2545	$166.25	$166.25	$166.30
Purchase #6	$182.74	4.172%	$190.3639	$190.36	$190.35	$190.40
Purchase #7	$150.53	9.258%	$164.4661	$164.47	$164.45	$164.50
7 purchase totals =	$971.34		$1,043.8099	$1,043.81	$1,043.80	$1,044.00