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	$133.52	5.277%	$140.5659	$140.57	$140.55	$140.60
Purchase #2	$112.27	11.640%	$125.3382	$125.34	$125.35	$125.30
Purchase #3	$152.60	9.853%	$167.6357	$167.64	$167.65	$167.60
Purchase #4	$223.99	7.741%	$241.3291	$241.33	$241.35	$241.30
Purchase #5	$72.94	7.525%	$78.4287	$78.43	$78.45	$78.40
Purchase #6	$119.42	6.811%	$127.5537	$127.55	$127.55	$127.60
Purchase #7	$186.38	3.387%	$192.6927	$192.69	$192.70	$192.70
7 purchase totals =	$1,001.12		$1,073.5440	$1,073.55	$1,073.60	$1,073.50