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	$100.55	5.116%	$105.6941	$105.69	$105.70	$105.70
Purchase #2	$100.96	5.466%	$106.4785	$106.48	$106.50	$106.50
Purchase #3	$173.75	3.216%	$179.3378	$179.34	$179.35	$179.30
Purchase #4	$216.38	7.604%	$232.8335	$232.83	$232.85	$232.80
Purchase #5	$244.29	4.585%	$255.4907	$255.49	$255.50	$255.50
Purchase #6	$118.41	5.470%	$124.887	$124.89	$124.90	$124.90
Purchase #7	$55.90	6.545%	$59.5587	$59.56	$59.55	$59.60
7 purchase totals =	$1,010.24		$1,064.2803	$1,064.28	$1,064.35	$1,064.30