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	$226.56	5.344%	$238.6674	$238.67	$238.65	$238.70
Purchase #2	$53.86	10.273%	$59.393	$59.39	$59.40	$59.40
Purchase #3	$240.54	6.560%	$256.3194	$256.32	$256.30	$256.30
Purchase #4	$243.93	12.143%	$273.5504	$273.55	$273.55	$273.60
Purchase #5	$83.91	7.136%	$89.8978	$89.90	$89.90	$89.90
Purchase #6	$223.51	13.238%	$253.0983	$253.10	$253.10	$253.10
Purchase #7	$29.32	9.268%	$32.0374	$32.04	$32.05	$32.00
7 purchase totals =	$1,101.63		$1,202.9637	$1,202.97	$1,202.95	$1,203.00