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	$85.75	12.139%	$96.1592	$96.16	$96.15	$96.20
Purchase #2	$127.44	3.641%	$132.0801	$132.08	$132.10	$132.10
Purchase #3	$128.26	12.621%	$144.4477	$144.45	$144.45	$144.40
Purchase #4	$203.33	12.533%	$228.8133	$228.81	$228.80	$228.80
Purchase #5	$52.83	11.671%	$58.9958	$59.00	$59.00	$59.00
Purchase #6	$219.89	6.819%	$234.8843	$234.88	$234.90	$234.90
Purchase #7	$207.89	4.164%	$216.5465	$216.55	$216.55	$216.50
7 purchase totals =	$1,025.39		$1,111.9269	$1,111.93	$1,111.95	$1,111.90