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	$235.46	11.201%	$261.8339	$261.83	$261.85	$261.80
Purchase #2	$50.66	11.206%	$56.337	$56.34	$56.35	$56.30
Purchase #3	$242.88	4.589%	$254.0258	$254.03	$254.05	$254.00
Purchase #4	$81.73	6.384%	$86.9476	$86.95	$86.95	$86.90
Purchase #5	$172.46	4.309%	$179.8913	$179.89	$179.90	$179.90
Purchase #6	$102.55	6.408%	$109.1214	$109.12	$109.10	$109.10
Purchase #7	$200.57	10.806%	$222.2436	$222.24	$222.25	$222.20
7 purchase totals =	$1,086.31		$1,170.4006	$1,170.40	$1,170.45	$1,170.20