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	$240.90	9.725%	$264.3275	$264.33	$264.35	$264.30
Purchase #2	$232.79	13.240%	$263.6114	$263.61	$263.60	$263.60
Purchase #3	$68.69	5.403%	$72.4013	$72.40	$72.40	$72.40
Purchase #4	$163.64	12.808%	$184.599	$184.60	$184.60	$184.60
Purchase #5	$84.36	6.570%	$89.9025	$89.90	$89.90	$89.90
Purchase #6	$34.49	10.270%	$38.0321	$38.03	$38.05	$38.00
Purchase #7	$238.32	7.270%	$255.6459	$255.65	$255.65	$255.60
7 purchase totals =	$1,063.19		$1,168.5197	$1,168.52	$1,168.55	$1,168.40