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	$148.48	3.419%	$153.5565	$153.56	$153.55	$153.60
Purchase #2	$125.53	8.403%	$136.0783	$136.08	$136.10	$136.10
Purchase #3	$39.88	6.640%	$42.528	$42.53	$42.55	$42.50
Purchase #4	$237.72	11.617%	$265.3359	$265.34	$265.35	$265.30
Purchase #5	$155.32	6.165%	$164.8955	$164.90	$164.90	$164.90
Purchase #6	$142.89	6.726%	$152.5008	$152.50	$152.50	$152.50
Purchase #7	$126.95	9.146%	$138.5608	$138.56	$138.55	$138.60
7 purchase totals =	$976.77		$1,053.4558	$1,053.47	$1,053.50	$1,053.50