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	$168.34	8.159%	$182.0749	$182.07	$182.05	$182.10
Purchase #2	$33.93	10.296%	$37.4234	$37.42	$37.40	$37.40
Purchase #3	$152.35	6.134%	$161.6951	$161.70	$161.70	$161.70
Purchase #4	$158.35	6.380%	$168.4527	$168.45	$168.45	$168.50
Purchase #5	$77.35	7.175%	$82.8999	$82.90	$82.90	$82.90
Purchase #6	$247.54	3.605%	$256.4638	$256.46	$256.45	$256.50
Purchase #7	$41.81	3.116%	$43.1128	$43.11	$43.10	$43.10
7 purchase totals =	$879.67		$932.1226	$932.11	$932.05	$932.20