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	$213.90	5.316%	$225.2709	$225.27	$225.25	$225.30
Purchase #2	$178.37	12.516%	$200.6948	$200.69	$200.70	$200.70
Purchase #3	$164.92	5.581%	$174.1242	$174.12	$174.10	$174.10
Purchase #4	$156.48	5.435%	$164.9847	$164.98	$165.00	$165.00
Purchase #5	$18.42	3.724%	$19.106	$19.11	$19.10	$19.10
Purchase #6	$243.76	3.113%	$251.3482	$251.35	$251.35	$251.30
Purchase #7	$23.76	11.153%	$26.41	$26.41	$26.40	$26.40
7 purchase totals =	$999.61		$1,061.9388	$1,061.93	$1,061.90	$1,061.90