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	$147.27	10.651%	$162.9557	$162.96	$162.95	$163.00
Purchase #2	$162.53	10.382%	$179.4039	$179.40	$179.40	$179.40
Purchase #3	$221.51	12.117%	$248.3504	$248.35	$248.35	$248.40
Purchase #4	$96.60	9.231%	$105.5171	$105.52	$105.50	$105.50
Purchase #5	$38.86	4.494%	$40.6064	$40.61	$40.60	$40.60
Purchase #6	$195.81	5.512%	$206.603	$206.60	$206.60	$206.60
Purchase #7	$207.94	6.269%	$220.9758	$220.98	$221.00	$221.00
7 purchase totals =	$1,070.52		$1,164.4123	$1,164.42	$1,164.40	$1,164.50