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	$40.51	8.264%	$43.8577	$43.86	$43.85	$43.90
Purchase #2	$200.44	8.126%	$216.7278	$216.73	$216.75	$216.70
Purchase #3	$243.32	12.784%	$274.426	$274.43	$274.45	$274.40
Purchase #4	$69.68	12.264%	$78.2256	$78.23	$78.25	$78.20
Purchase #5	$118.68	10.346%	$130.9586	$130.96	$130.95	$131.00
Purchase #6	$139.44	10.114%	$153.543	$153.54	$153.55	$153.50
Purchase #7	$156.78	3.399%	$162.109	$162.11	$162.10	$162.10
7 purchase totals =	$968.85		$1,059.8477	$1,059.86	$1,059.90	$1,059.80