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	$123.66	5.114%	$129.984	$129.98	$130.00	$130.00
Purchase #2	$55.48	6.833%	$59.2709	$59.27	$59.25	$59.30
Purchase #3	$153.66	11.627%	$171.526	$171.53	$171.55	$171.50
Purchase #4	$163.67	13.351%	$185.5216	$185.52	$185.50	$185.50
Purchase #5	$197.76	7.307%	$212.2103	$212.21	$212.20	$212.20
Purchase #6	$180.80	3.208%	$186.6001	$186.60	$186.60	$186.60
Purchase #7	$151.32	5.859%	$160.1858	$160.19	$160.20	$160.20
7 purchase totals =	$1,026.35		$1,105.2987	$1,105.30	$1,105.30	$1,105.30