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	$216.53	7.672%	$233.1422	$233.14	$233.15	$233.10
Purchase #2	$250.53	12.178%	$281.0395	$281.04	$281.05	$281.00
Purchase #3	$58.95	4.415%	$61.5526	$61.55	$61.55	$61.60
Purchase #4	$6.82	4.261%	$7.1106	$7.11	$7.10	$7.10
Purchase #5	$137.26	12.256%	$154.0826	$154.08	$154.10	$154.10
Purchase #6	$77.81	5.482%	$82.0755	$82.08	$82.10	$82.10
Purchase #7	$196.98	10.469%	$217.6018	$217.60	$217.60	$217.60
7 purchase totals =	$944.88		$1,036.6048	$1,036.60	$1,036.65	$1,036.60