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	$205.27	8.380%	$222.4716	$222.47	$222.45	$222.50
Purchase #2	$61.62	3.213%	$63.5999	$63.60	$63.60	$63.60
Purchase #3	$157.92	7.635%	$169.9772	$169.98	$170.00	$170.00
Purchase #4	$176.96	5.298%	$186.3353	$186.34	$186.35	$186.30
Purchase #5	$173.47	13.474%	$196.8433	$196.84	$196.85	$196.80
Purchase #6	$197.91	12.802%	$223.2464	$223.25	$223.25	$223.20
Purchase #7	$150.46	4.180%	$156.7492	$156.75	$156.75	$156.70
7 purchase totals =	$1,123.61		$1,219.2229	$1,219.23	$1,219.25	$1,219.10