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	$208.70	12.562%	$234.9169	$234.92	$234.90	$234.90
Purchase #2	$176.86	10.812%	$195.9821	$195.98	$196.00	$196.00
Purchase #3	$159.74	5.852%	$169.088	$169.09	$169.10	$169.10
Purchase #4	$27.43	3.565%	$28.4079	$28.41	$28.40	$28.40
Purchase #5	$189.57	9.640%	$207.8445	$207.84	$207.85	$207.80
Purchase #6	$90.42	11.576%	$100.887	$100.89	$100.90	$100.90
Purchase #7	$169.82	12.683%	$191.3583	$191.36	$191.35	$191.40
7 purchase totals =	$1,022.54		$1,128.4847	$1,128.49	$1,128.50	$1,128.50