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	$214.55	11.161%	$238.4959	$238.50	$238.50	$238.50
Purchase #2	$91.39	12.593%	$102.8987	$102.90	$102.90	$102.90
Purchase #3	$206.91	12.540%	$232.8565	$232.86	$232.85	$232.90
Purchase #4	$29.34	8.786%	$31.9178	$31.92	$31.90	$31.90
Purchase #5	$147.41	3.596%	$152.7109	$152.71	$152.70	$152.70
Purchase #6	$69.54	13.353%	$78.8257	$78.83	$78.85	$78.80
Purchase #7	$247.59	11.642%	$276.4144	$276.41	$276.40	$276.40
7 purchase totals =	$1,006.73		$1,114.1199	$1,114.13	$1,114.10	$1,114.10