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	$44.32	5.209%	$46.6286	$46.63	$46.65	$46.60
Purchase #2	$142.54	7.728%	$153.5555	$153.56	$153.55	$153.60
Purchase #3	$169.73	11.863%	$189.8651	$189.87	$189.85	$189.90
Purchase #4	$179.45	4.292%	$187.152	$187.15	$187.15	$187.20
Purchase #5	$128.57	5.680%	$135.8728	$135.87	$135.85	$135.90
Purchase #6	$178.25	10.120%	$196.2889	$196.29	$196.30	$196.30
Purchase #7	$227.47	7.673%	$244.9238	$244.92	$244.90	$244.90
7 purchase totals =	$1,070.33		$1,154.2867	$1,154.29	$1,154.25	$1,154.40