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	$214.57	4.770%	$224.805	$224.81	$224.80	$224.80
Purchase #2	$113.51	12.158%	$127.3105	$127.31	$127.30	$127.30
Purchase #3	$208.94	5.161%	$219.7234	$219.72	$219.70	$219.70
Purchase #4	$51.33	10.807%	$56.8772	$56.88	$56.90	$56.90
Purchase #5	$196.63	13.764%	$223.6942	$223.69	$223.70	$223.70
Purchase #6	$147.73	12.160%	$165.694	$165.69	$165.70	$165.70
Purchase #7	$72.85	5.693%	$76.9974	$77.00	$77.00	$77.00
7 purchase totals =	$1,005.56		$1,095.1017	$1,095.10	$1,095.10	$1,095.10