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	$166.68	10.720%	$184.5481	$184.55	$184.55	$184.50
Purchase #2	$44.64	4.228%	$46.5274	$46.53	$46.55	$46.50
Purchase #3	$219.78	6.123%	$233.2371	$233.24	$233.25	$233.20
Purchase #4	$88.94	12.336%	$99.9116	$99.91	$99.90	$99.90
Purchase #5	$25.44	8.844%	$27.6899	$27.69	$27.70	$27.70
Purchase #6	$167.53	5.149%	$176.1561	$176.16	$176.15	$176.20
Purchase #7	$232.57	10.260%	$256.4317	$256.43	$256.45	$256.40
7 purchase totals =	$945.58		$1,024.5019	$1,024.51	$1,024.55	$1,024.40