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	$62.94	4.111%	$65.5275	$65.53	$65.55	$65.50
Purchase #2	$20.63	4.731%	$21.606	$21.61	$21.60	$21.60
Purchase #3	$223.27	3.409%	$230.8813	$230.88	$230.90	$230.90
Purchase #4	$211.88	9.477%	$231.9599	$231.96	$231.95	$232.00
Purchase #5	$167.76	10.730%	$185.7606	$185.76	$185.75	$185.80
Purchase #6	$206.32	3.624%	$213.797	$213.80	$213.80	$213.80
Purchase #7	$222.45	9.376%	$243.3069	$243.31	$243.30	$243.30
7 purchase totals =	$1,115.25		$1,192.8392	$1,192.85	$1,192.85	$1,192.90