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	$43.72	6.262%	$46.4577	$46.46	$46.45	$46.50
Purchase #2	$173.44	6.418%	$184.5714	$184.57	$184.55	$184.60
Purchase #3	$171.43	6.511%	$182.5918	$182.59	$182.60	$182.60
Purchase #4	$163.35	3.161%	$168.5135	$168.51	$168.50	$168.50
Purchase #5	$243.38	10.543%	$269.0396	$269.04	$269.05	$269.00
Purchase #6	$109.71	11.713%	$122.5603	$122.56	$122.55	$122.60
Purchase #7	$234.56	8.410%	$254.2865	$254.29	$254.30	$254.30
7 purchase totals =	$1,139.59		$1,228.0208	$1,228.02	$1,228.00	$1,228.10