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	$117.98	7.675%	$127.035	$127.04	$127.05	$127.00
Purchase #2	$16.53	7.451%	$17.7617	$17.76	$17.75	$17.80
Purchase #3	$127.88	10.121%	$140.8227	$140.82	$140.80	$140.80
Purchase #4	$169.48	10.565%	$187.3856	$187.39	$187.40	$187.40
Purchase #5	$193.36	3.600%	$200.321	$200.32	$200.30	$200.30
Purchase #6	$31.80	12.455%	$35.7607	$35.76	$35.75	$35.80
Purchase #7	$126.31	8.662%	$137.251	$137.25	$137.25	$137.30
7 purchase totals =	$783.34		$846.3377	$846.34	$846.30	$846.40