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	$190.41	3.133%	$196.3755	$196.38	$196.40	$196.40
Purchase #2	$140.48	7.470%	$150.9739	$150.97	$150.95	$151.00
Purchase #3	$84.92	13.559%	$96.4343	$96.43	$96.45	$96.40
Purchase #4	$54.73	12.535%	$61.5904	$61.59	$61.60	$61.60
Purchase #5	$63.96	11.132%	$71.08	$71.08	$71.10	$71.10
Purchase #6	$97.48	3.716%	$101.1024	$101.10	$101.10	$101.10
Purchase #7	$23.47	10.521%	$25.9393	$25.94	$25.95	$25.90
7 purchase totals =	$655.45		$703.4958	$703.49	$703.55	$703.50