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	$164.56	4.464%	$171.906	$171.91	$171.90	$171.90
Purchase #2	$13.34	10.739%	$14.7726	$14.77	$14.75	$14.80
Purchase #3	$41.51	10.403%	$45.8283	$45.83	$45.85	$45.80
Purchase #4	$94.51	3.106%	$97.4455	$97.45	$97.45	$97.40
Purchase #5	$167.51	3.817%	$173.9039	$173.90	$173.90	$173.90
Purchase #6	$137.30	10.540%	$151.7714	$151.77	$151.75	$151.80
Purchase #7	$106.49	13.422%	$120.7831	$120.78	$120.80	$120.80
7 purchase totals =	$725.22		$776.4108	$776.41	$776.40	$776.40