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	$116.98	5.463%	$123.3706	$123.37	$123.35	$123.40
Purchase #2	$214.37	4.111%	$223.1828	$223.18	$223.20	$223.20
Purchase #3	$237.71	10.289%	$262.168	$262.17	$262.15	$262.20
Purchase #4	$158.44	3.749%	$164.3799	$164.38	$164.40	$164.40
Purchase #5	$92.73	4.320%	$96.7359	$96.74	$96.75	$96.70
Purchase #6	$167.55	11.136%	$186.2084	$186.21	$186.20	$186.20
Purchase #7	$15.78	11.550%	$17.6026	$17.60	$17.60	$17.60
7 purchase totals =	$1,003.56		$1,073.6482	$1,073.65	$1,073.65	$1,073.70