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	$62.41	7.392%	$67.0233	$67.02	$67.00	$67.00
Purchase #2	$200.62	6.146%	$212.9501	$212.95	$212.95	$213.00
Purchase #3	$100.39	13.609%	$114.0521	$114.05	$114.05	$114.10
Purchase #4	$103.46	12.257%	$116.1411	$116.14	$116.15	$116.10
Purchase #5	$93.48	3.273%	$96.5396	$96.54	$96.55	$96.50
Purchase #6	$147.31	3.782%	$152.8813	$152.88	$152.90	$152.90
Purchase #7	$241.62	8.396%	$261.9064	$261.91	$261.90	$261.90
7 purchase totals =	$949.29		$1,021.4939	$1,021.49	$1,021.50	$1,021.50