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	$56.44	7.388%	$60.6098	$60.61	$60.60	$60.60
Purchase #2	$53.96	5.849%	$57.1161	$57.12	$57.10	$57.10
Purchase #3	$135.71	4.342%	$141.6025	$141.60	$141.60	$141.60
Purchase #4	$200.46	9.717%	$219.9387	$219.94	$219.95	$219.90
Purchase #5	$218.54	12.802%	$246.5175	$246.52	$246.50	$246.50
Purchase #6	$236.95	6.269%	$251.8044	$251.80	$251.80	$251.80
Purchase #7	$70.55	11.337%	$78.5483	$78.55	$78.55	$78.50
7 purchase totals =	$972.61		$1,056.1373	$1,056.14	$1,056.10	$1,056.00