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	$105.34	11.261%	$117.2023	$117.20	$117.20	$117.20
Purchase #2	$166.31	11.253%	$185.0249	$185.02	$185.00	$185.00
Purchase #3	$9.38	12.158%	$10.5204	$10.52	$10.50	$10.50
Purchase #4	$201.93	4.855%	$211.7337	$211.73	$211.75	$211.70
Purchase #5	$104.43	13.838%	$118.881	$118.88	$118.90	$118.90
Purchase #6	$243.89	9.774%	$267.7278	$267.73	$267.75	$267.70
Purchase #7	$141.40	6.172%	$150.1272	$150.13	$150.15	$150.10
7 purchase totals =	$972.68		$1,061.2173	$1,061.21	$1,061.25	$1,061.10