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	$136.87	9.812%	$150.2997	$150.30	$150.30	$150.30
Purchase #2	$10.73	7.555%	$11.5407	$11.54	$11.55	$11.50
Purchase #3	$137.80	3.172%	$142.171	$142.17	$142.15	$142.20
Purchase #4	$78.57	4.518%	$82.1198	$82.12	$82.10	$82.10
Purchase #5	$184.79	5.458%	$194.8758	$194.88	$194.90	$194.90
Purchase #6	$203.98	6.133%	$216.4901	$216.49	$216.50	$216.50
Purchase #7	$116.55	9.437%	$127.5488	$127.55	$127.55	$127.50
7 purchase totals =	$869.29		$925.0459	$925.05	$925.05	$925.00