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	$171.98	5.860%	$182.058	$182.06	$182.05	$182.10
Purchase #2	$51.28	4.350%	$53.5107	$53.51	$53.50	$53.50
Purchase #3	$148.59	11.774%	$166.085	$166.09	$166.10	$166.10
Purchase #4	$202.43	6.160%	$214.8997	$214.90	$214.90	$214.90
Purchase #5	$180.51	5.501%	$190.4399	$190.44	$190.45	$190.40
Purchase #6	$198.43	8.620%	$215.5347	$215.53	$215.55	$215.50
Purchase #7	$203.27	7.767%	$219.058	$219.06	$219.05	$219.10
7 purchase totals =	$1,156.49		$1,241.5860	$1,241.59	$1,241.60	$1,241.60