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	$219.78	11.870%	$245.8679	$245.87	$245.85	$245.90
Purchase #2	$221.83	3.416%	$229.4077	$229.41	$229.40	$229.40
Purchase #3	$246.53	12.559%	$277.4917	$277.49	$277.50	$277.50
Purchase #4	$46.94	12.166%	$52.6507	$52.65	$52.65	$52.70
Purchase #5	$142.52	9.478%	$156.028	$156.03	$156.05	$156.00
Purchase #6	$109.41	13.350%	$124.0162	$124.02	$124.00	$124.00
Purchase #7	$104.93	6.232%	$111.4692	$111.47	$111.45	$111.50
7 purchase totals =	$1,091.94		$1,196.9314	$1,196.94	$1,196.90	$1,197.00