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	$213.83	6.285%	$227.2692	$227.27	$227.25	$227.30
Purchase #2	$192.36	5.558%	$203.0514	$203.05	$203.05	$203.10
Purchase #3	$197.83	4.214%	$206.1666	$206.17	$206.15	$206.20
Purchase #4	$112.90	6.643%	$120.3999	$120.40	$120.40	$120.40
Purchase #5	$74.57	5.172%	$78.4268	$78.43	$78.45	$78.40
Purchase #6	$201.69	10.585%	$223.0389	$223.04	$223.05	$223.00
Purchase #7	$41.39	9.371%	$45.2687	$45.27	$45.25	$45.30
7 purchase totals =	$1,034.57		$1,103.6215	$1,103.63	$1,103.60	$1,103.70