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	$156.40	9.814%	$171.7491	$171.75	$171.75	$171.70
Purchase #2	$232.34	3.648%	$240.8158	$240.82	$240.80	$240.80
Purchase #3	$215.71	4.684%	$225.8139	$225.81	$225.80	$225.80
Purchase #4	$121.64	3.306%	$125.6614	$125.66	$125.65	$125.70
Purchase #5	$73.89	5.834%	$78.2007	$78.20	$78.20	$78.20
Purchase #6	$164.41	4.370%	$171.5947	$171.59	$171.60	$171.60
Purchase #7	$10.76	12.798%	$12.1371	$12.14	$12.15	$12.10
7 purchase totals =	$975.15		$1,025.9727	$1,025.97	$1,025.95	$1,025.90