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	$103.57	8.829%	$112.7142	$112.71	$112.70	$112.70
Purchase #2	$19.32	8.247%	$20.9133	$20.91	$20.90	$20.90
Purchase #3	$100.86	4.449%	$105.3473	$105.35	$105.35	$105.30
Purchase #4	$244.73	12.359%	$274.9762	$274.98	$275.00	$275.00
Purchase #5	$244.37	5.586%	$258.0205	$258.02	$258.00	$258.00
Purchase #6	$185.59	6.462%	$197.5828	$197.58	$197.60	$197.60
Purchase #7	$46.98	13.479%	$53.3124	$53.31	$53.30	$53.30
7 purchase totals =	$945.42		$1,022.8667	$1,022.86	$1,022.85	$1,022.80