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	$190.76	13.591%	$216.6862	$216.69	$216.70	$216.70
Purchase #2	$192.59	13.653%	$218.8843	$218.88	$218.90	$218.90
Purchase #3	$80.98	6.151%	$85.9611	$85.96	$85.95	$86.00
Purchase #4	$132.90	6.227%	$141.1757	$141.18	$141.20	$141.20
Purchase #5	$155.43	10.541%	$171.8139	$171.81	$171.80	$171.80
Purchase #6	$228.62	13.452%	$259.374	$259.37	$259.35	$259.40
Purchase #7	$69.35	3.298%	$71.6372	$71.64	$71.65	$71.60
7 purchase totals =	$1,050.63		$1,165.5324	$1,165.53	$1,165.55	$1,165.60