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	$113.76	10.176%	$125.3362	$125.34	$125.35	$125.30
Purchase #2	$136.39	3.820%	$141.6001	$141.60	$141.60	$141.60
Purchase #3	$160.43	5.717%	$169.6018	$169.60	$169.60	$169.60
Purchase #4	$158.49	12.847%	$178.8512	$178.85	$178.85	$178.90
Purchase #5	$240.52	12.618%	$270.8688	$270.87	$270.85	$270.90
Purchase #6	$157.77	10.554%	$174.421	$174.42	$174.40	$174.40
Purchase #7	$188.92	3.105%	$194.786	$194.79	$194.80	$194.80
7 purchase totals =	$1,156.28		$1,255.4651	$1,255.47	$1,255.45	$1,255.50