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	$66.63	8.367%	$72.2049	$72.20	$72.20	$72.20
Purchase #2	$113.93	8.721%	$123.8658	$123.87	$123.85	$123.90
Purchase #3	$157.82	5.109%	$165.883	$165.88	$165.90	$165.90
Purchase #4	$203.77	7.577%	$219.2097	$219.21	$219.20	$219.20
Purchase #5	$145.25	13.640%	$165.0621	$165.06	$165.05	$165.10
Purchase #6	$96.34	9.680%	$105.6657	$105.67	$105.65	$105.70
Purchase #7	$246.41	6.603%	$262.6805	$262.68	$262.70	$262.70
7 purchase totals =	$1,030.15		$1,114.5717	$1,114.57	$1,114.55	$1,114.70