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	$114.68	11.225%	$127.5528	$127.55	$127.55	$127.60
Purchase #2	$141.55	11.784%	$158.2303	$158.23	$158.25	$158.20
Purchase #3	$247.50	4.819%	$259.427	$259.43	$259.45	$259.40
Purchase #4	$230.64	4.743%	$241.5793	$241.58	$241.60	$241.60
Purchase #5	$71.60	9.432%	$78.3533	$78.35	$78.35	$78.40
Purchase #6	$90.42	10.175%	$99.6202	$99.62	$99.60	$99.60
Purchase #7	$37.98	7.279%	$40.7446	$40.74	$40.75	$40.70
7 purchase totals =	$934.37		$1,005.5075	$1,005.50	$1,005.55	$1,005.50