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	$241.76	10.752%	$267.754	$267.75	$267.75	$267.80
Purchase #2	$40.71	4.279%	$42.452	$42.45	$42.45	$42.50
Purchase #3	$142.68	9.513%	$156.2531	$156.25	$156.25	$156.30
Purchase #4	$59.82	4.516%	$62.5215	$62.52	$62.50	$62.50
Purchase #5	$113.77	4.140%	$118.4801	$118.48	$118.50	$118.50
Purchase #6	$232.79	11.830%	$260.3291	$260.33	$260.35	$260.30
Purchase #7	$234.72	10.780%	$260.0228	$260.02	$260.00	$260.00
7 purchase totals =	$1,066.25		$1,167.8126	$1,167.80	$1,167.80	$1,167.90