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	$88.34	8.684%	$96.0114	$96.01	$96.00	$96.00
Purchase #2	$144.39	12.793%	$162.8618	$162.86	$162.85	$162.90
Purchase #3	$189.60	10.538%	$209.58	$209.58	$209.60	$209.60
Purchase #4	$58.57	8.718%	$63.6761	$63.68	$63.70	$63.70
Purchase #5	$237.87	11.660%	$265.6056	$265.61	$265.60	$265.60
Purchase #6	$207.53	12.711%	$233.9091	$233.91	$233.90	$233.90
Purchase #7	$184.29	6.851%	$196.9157	$196.92	$196.90	$196.90
7 purchase totals =	$1,110.59		$1,228.5597	$1,228.57	$1,228.55	$1,228.60