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	$224.98	12.706%	$253.566	$253.57	$253.55	$253.60
Purchase #2	$80.83	6.321%	$85.9393	$85.94	$85.95	$85.90
Purchase #3	$84.33	11.776%	$94.2607	$94.26	$94.25	$94.30
Purchase #4	$70.37	11.779%	$78.6589	$78.66	$78.65	$78.70
Purchase #5	$135.56	11.555%	$151.224	$151.22	$151.20	$151.20
Purchase #6	$235.81	3.445%	$243.9337	$243.93	$243.95	$243.90
Purchase #7	$109.91	7.406%	$118.0499	$118.05	$118.05	$118.00
7 purchase totals =	$941.79		$1,025.6325	$1,025.63	$1,025.60	$1,025.60