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	$41.69	9.548%	$45.6706	$45.67	$45.65	$45.70
Purchase #2	$41.82	4.794%	$43.8249	$43.82	$43.80	$43.80
Purchase #3	$176.66	4.331%	$184.3111	$184.31	$184.30	$184.30
Purchase #4	$217.27	12.362%	$244.1289	$244.13	$244.15	$244.10
Purchase #5	$164.45	8.757%	$178.8509	$178.85	$178.85	$178.90
Purchase #6	$130.68	4.731%	$136.8625	$136.86	$136.85	$136.90
Purchase #7	$173.98	5.688%	$183.876	$183.88	$183.90	$183.90
7 purchase totals =	$946.55		$1,017.5249	$1,017.52	$1,017.50	$1,017.60