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	$58.30	5.247%	$61.359	$61.36	$61.35	$61.40
Purchase #2	$62.30	7.609%	$67.0404	$67.04	$67.05	$67.00
Purchase #3	$31.45	11.805%	$35.1627	$35.16	$35.15	$35.20
Purchase #4	$246.82	4.534%	$258.0108	$258.01	$258.00	$258.00
Purchase #5	$44.75	3.720%	$46.4147	$46.41	$46.40	$46.40
Purchase #6	$185.77	4.363%	$193.8751	$193.88	$193.90	$193.90
Purchase #7	$98.35	11.402%	$109.5639	$109.56	$109.55	$109.60
7 purchase totals =	$727.74		$771.4266	$771.42	$771.40	$771.50