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	$172.32	11.464%	$192.0748	$192.07	$192.05	$192.10
Purchase #2	$78.43	12.389%	$88.1467	$88.15	$88.15	$88.10
Purchase #3	$24.34	11.111%	$27.0444	$27.04	$27.05	$27.00
Purchase #4	$246.85	12.833%	$278.5283	$278.53	$278.55	$278.50
Purchase #5	$227.93	7.635%	$245.3325	$245.33	$245.35	$245.30
Purchase #6	$192.84	6.535%	$205.4421	$205.44	$205.45	$205.40
Purchase #7	$55.43	6.668%	$59.1261	$59.13	$59.15	$59.10
7 purchase totals =	$998.14		$1,095.6949	$1,095.69	$1,095.75	$1,095.50