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	$175.82	4.658%	$184.0097	$184.01	$184.00	$184.00
Purchase #2	$165.61	11.758%	$185.0824	$185.08	$185.10	$185.10
Purchase #3	$34.86	7.183%	$37.364	$37.36	$37.35	$37.40
Purchase #4	$194.81	4.451%	$203.481	$203.48	$203.50	$203.50
Purchase #5	$114.30	3.676%	$118.5017	$118.50	$118.50	$118.50
Purchase #6	$171.46	12.243%	$192.4518	$192.45	$192.45	$192.50
Purchase #7	$170.71	11.507%	$190.3536	$190.35	$190.35	$190.40
7 purchase totals =	$1,027.57		$1,111.2442	$1,111.23	$1,111.25	$1,111.40