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	$62.50	7.287%	$67.0544	$67.05	$67.05	$67.10
Purchase #2	$154.90	6.582%	$165.0955	$165.10	$165.10	$165.10
Purchase #3	$183.54	5.120%	$192.9372	$192.94	$192.95	$192.90
Purchase #4	$192.73	3.323%	$199.1344	$199.13	$199.15	$199.10
Purchase #5	$103.63	9.715%	$113.6977	$113.70	$113.70	$113.70
Purchase #6	$125.44	11.852%	$140.3071	$140.31	$140.30	$140.30
Purchase #7	$150.67	7.610%	$162.136	$162.14	$162.15	$162.10
7 purchase totals =	$973.41		$1,040.3623	$1,040.37	$1,040.40	$1,040.30