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	$118.50	12.632%	$133.4689	$133.47	$133.45	$133.50
Purchase #2	$224.73	13.805%	$255.754	$255.75	$255.75	$255.80
Purchase #3	$249.47	3.516%	$258.2414	$258.24	$258.25	$258.20
Purchase #4	$114.81	3.428%	$118.7457	$118.75	$118.75	$118.70
Purchase #5	$50.32	12.513%	$56.6165	$56.62	$56.60	$56.60
Purchase #6	$139.90	3.198%	$144.374	$144.37	$144.35	$144.40
Purchase #7	$52.47	3.498%	$54.3054	$54.31	$54.30	$54.30
7 purchase totals =	$950.20		$1,021.5059	$1,021.51	$1,021.45	$1,021.50