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	$41.36	11.505%	$46.1185	$46.12	$46.10	$46.10
Purchase #2	$41.99	3.642%	$43.5193	$43.52	$43.50	$43.50
Purchase #3	$249.39	8.157%	$269.7327	$269.73	$269.75	$269.70
Purchase #4	$179.32	13.475%	$203.4834	$203.48	$203.50	$203.50
Purchase #5	$55.35	8.146%	$59.8588	$59.86	$59.85	$59.90
Purchase #6	$163.31	11.770%	$182.5316	$182.53	$182.55	$182.50
Purchase #7	$249.38	3.465%	$258.021	$258.02	$258.00	$258.00
7 purchase totals =	$980.10		$1,063.2653	$1,063.26	$1,063.25	$1,063.20