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	$219.53	10.508%	$242.5982	$242.60	$242.60	$242.60
Purchase #2	$96.31	7.117%	$103.1644	$103.16	$103.15	$103.20
Purchase #3	$163.77	9.518%	$179.3576	$179.36	$179.35	$179.40
Purchase #4	$54.63	9.612%	$59.881	$59.88	$59.90	$59.90
Purchase #5	$28.85	13.601%	$32.7739	$32.77	$32.75	$32.80
Purchase #6	$207.61	5.767%	$219.5829	$219.58	$219.60	$219.60
Purchase #7	$247.99	9.219%	$270.8522	$270.85	$270.85	$270.90
7 purchase totals =	$1,018.69		$1,108.2102	$1,108.20	$1,108.20	$1,108.40