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	$217.63	11.311%	$242.2461	$242.25	$242.25	$242.20
Purchase #2	$60.56	3.798%	$62.8601	$62.86	$62.85	$62.90
Purchase #3	$54.84	7.796%	$59.1153	$59.12	$59.10	$59.10
Purchase #4	$177.62	10.409%	$196.1085	$196.11	$196.10	$196.10
Purchase #5	$218.40	11.538%	$243.599	$243.60	$243.60	$243.60
Purchase #6	$138.70	11.755%	$155.0042	$155.00	$155.00	$155.00
Purchase #7	$220.71	11.829%	$246.8178	$246.82	$246.80	$246.80
7 purchase totals =	$1,088.46		$1,205.7510	$1,205.76	$1,205.70	$1,205.70