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	$112.45	3.364%	$116.2328	$116.23	$116.25	$116.20
Purchase #2	$92.77	7.256%	$99.5014	$99.50	$99.50	$99.50
Purchase #3	$245.63	7.248%	$263.4333	$263.43	$263.45	$263.40
Purchase #4	$104.91	13.136%	$118.691	$118.69	$118.70	$118.70
Purchase #5	$110.34	12.732%	$124.3885	$124.39	$124.40	$124.40
Purchase #6	$150.31	9.525%	$164.627	$164.63	$164.65	$164.60
Purchase #7	$194.76	6.847%	$208.0952	$208.10	$208.10	$208.10
7 purchase totals =	$1,011.17		$1,094.9692	$1,094.97	$1,095.05	$1,094.90