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	$118.66	7.254%	$127.2676	$127.27	$127.25	$127.30
Purchase #2	$239.59	7.458%	$257.4586	$257.46	$257.45	$257.50
Purchase #3	$34.83	7.743%	$37.5269	$37.53	$37.55	$37.50
Purchase #4	$8.83	6.155%	$9.3735	$9.37	$9.35	$9.40
Purchase #5	$176.31	11.572%	$196.7126	$196.71	$196.70	$196.70
Purchase #6	$7.60	13.404%	$8.6187	$8.62	$8.60	$8.60
Purchase #7	$121.84	4.458%	$127.2716	$127.27	$127.25	$127.30
7 purchase totals =	$707.66		$764.2295	$764.23	$764.15	$764.30