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	$64.59	10.813%	$71.5741	$71.57	$71.55	$71.60
Purchase #2	$156.85	10.325%	$173.0448	$173.04	$173.05	$173.00
Purchase #3	$185.57	4.844%	$194.559	$194.56	$194.55	$194.60
Purchase #4	$132.60	10.827%	$146.9566	$146.96	$146.95	$147.00
Purchase #5	$126.63	11.192%	$140.8024	$140.80	$140.80	$140.80
Purchase #6	$109.46	13.687%	$124.4418	$124.44	$124.45	$124.40
Purchase #7	$184.77	8.530%	$200.5309	$200.53	$200.55	$200.50
7 purchase totals =	$960.47		$1,051.9096	$1,051.90	$1,051.90	$1,051.90