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	$90.55	7.187%	$97.0578	$97.06	$97.05	$97.10
Purchase #2	$123.65	13.774%	$140.6816	$140.68	$140.70	$140.70
Purchase #3	$71.34	10.369%	$78.7372	$78.74	$78.75	$78.70
Purchase #4	$145.92	10.385%	$161.0738	$161.07	$161.05	$161.10
Purchase #5	$207.27	7.469%	$222.751	$222.75	$222.75	$222.80
Purchase #6	$219.29	10.151%	$241.5501	$241.55	$241.55	$241.60
Purchase #7	$203.54	9.352%	$222.5751	$222.58	$222.60	$222.60
7 purchase totals =	$1,061.56		$1,164.4266	$1,164.43	$1,164.45	$1,164.60