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	$148.80	10.572%	$164.5311	$164.53	$164.55	$164.50
Purchase #2	$70.26	4.220%	$73.225	$73.23	$73.25	$73.20
Purchase #3	$190.53	13.328%	$215.9238	$215.92	$215.90	$215.90
Purchase #4	$238.92	10.463%	$263.9182	$263.92	$263.90	$263.90
Purchase #5	$198.57	6.184%	$210.8496	$210.85	$210.85	$210.80
Purchase #6	$33.43	10.441%	$36.9204	$36.92	$36.90	$36.90
Purchase #7	$95.96	13.600%	$109.0106	$109.01	$109.00	$109.00
7 purchase totals =	$976.47		$1,074.3787	$1,074.38	$1,074.35	$1,074.20