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	$222.57	5.776%	$235.4256	$235.43	$235.45	$235.40
Purchase #2	$99.34	4.600%	$103.9096	$103.91	$103.90	$103.90
Purchase #3	$85.67	11.787%	$95.7679	$95.77	$95.75	$95.80
Purchase #4	$81.76	13.490%	$92.7894	$92.79	$92.80	$92.80
Purchase #5	$149.61	9.817%	$164.2972	$164.30	$164.30	$164.30
Purchase #6	$165.58	6.227%	$175.8907	$175.89	$175.90	$175.90
Purchase #7	$163.37	10.484%	$180.4977	$180.50	$180.50	$180.50
7 purchase totals =	$967.90		$1,048.5781	$1,048.59	$1,048.60	$1,048.60