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	$184.88	6.401%	$196.7142	$196.71	$196.70	$196.70
Purchase #2	$178.40	9.326%	$195.0376	$195.04	$195.05	$195.00
Purchase #3	$94.72	6.669%	$101.0369	$101.04	$101.05	$101.00
Purchase #4	$157.47	4.602%	$164.7168	$164.72	$164.70	$164.70
Purchase #5	$131.78	11.560%	$147.0138	$147.01	$147.00	$147.00
Purchase #6	$30.51	3.678%	$31.6322	$31.63	$31.65	$31.60
Purchase #7	$178.96	10.844%	$198.3664	$198.37	$198.35	$198.40
7 purchase totals =	$956.72		$1,034.5179	$1,034.52	$1,034.50	$1,034.40