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	$175.66	12.187%	$197.0677	$197.07	$197.05	$197.10
Purchase #2	$205.83	8.797%	$223.9369	$223.94	$223.95	$223.90
Purchase #3	$185.57	8.264%	$200.9055	$200.91	$200.90	$200.90
Purchase #4	$187.78	4.441%	$196.1193	$196.12	$196.10	$196.10
Purchase #5	$132.80	12.671%	$149.6271	$149.63	$149.65	$149.60
Purchase #6	$104.70	5.223%	$110.1685	$110.17	$110.15	$110.20
Purchase #7	$105.52	12.211%	$118.405	$118.41	$118.40	$118.40
7 purchase totals =	$1,097.86		$1,196.2300	$1,196.25	$1,196.20	$1,196.20