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	$119.84	6.331%	$127.4271	$127.43	$127.45	$127.40
Purchase #2	$168.59	10.301%	$185.9565	$185.96	$185.95	$186.00
Purchase #3	$68.63	3.493%	$71.0272	$71.03	$71.05	$71.00
Purchase #4	$243.52	10.654%	$269.4646	$269.46	$269.45	$269.50
Purchase #5	$181.47	13.778%	$206.4729	$206.47	$206.45	$206.50
Purchase #6	$202.94	8.255%	$219.6927	$219.69	$219.70	$219.70
Purchase #7	$29.87	5.807%	$31.6046	$31.60	$31.60	$31.60
7 purchase totals =	$1,014.86		$1,111.6456	$1,111.64	$1,111.65	$1,111.70