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	$152.45	10.447%	$168.3765	$168.38	$168.40	$168.40
Purchase #2	$38.88	6.842%	$41.5402	$41.54	$41.55	$41.50
Purchase #3	$62.36	4.812%	$65.3608	$65.36	$65.35	$65.40
Purchase #4	$162.75	3.849%	$169.0142	$169.01	$169.00	$169.00
Purchase #5	$86.38	6.753%	$92.2132	$92.21	$92.20	$92.20
Purchase #6	$57.84	12.260%	$64.9312	$64.93	$64.95	$64.90
Purchase #7	$198.72	3.245%	$205.1685	$205.17	$205.15	$205.20
7 purchase totals =	$759.38		$806.6046	$806.60	$806.60	$806.60