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	$145.40	4.721%	$152.2643	$152.26	$152.25	$152.30
Purchase #2	$10.73	3.659%	$11.1226	$11.12	$11.10	$11.10
Purchase #3	$67.89	6.743%	$72.4678	$72.47	$72.45	$72.50
Purchase #4	$36.37	5.245%	$38.2776	$38.28	$38.30	$38.30
Purchase #5	$56.47	9.121%	$61.6206	$61.62	$61.60	$61.60
Purchase #6	$86.56	11.706%	$96.6927	$96.69	$96.70	$96.70
Purchase #7	$204.77	6.161%	$217.3859	$217.39	$217.40	$217.40
7 purchase totals =	$608.19		$649.8315	$649.83	$649.80	$649.90