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	$152.55	4.784%	$159.848	$159.85	$159.85	$159.80
Purchase #2	$150.67	7.516%	$161.9944	$161.99	$162.00	$162.00
Purchase #3	$113.52	4.285%	$118.3843	$118.38	$118.40	$118.40
Purchase #4	$171.59	8.134%	$185.5471	$185.55	$185.55	$185.50
Purchase #5	$108.41	9.406%	$118.607	$118.61	$118.60	$118.60
Purchase #6	$224.48	6.171%	$238.3327	$238.33	$238.35	$238.30
Purchase #7	$120.40	11.105%	$133.7704	$133.77	$133.75	$133.80
7 purchase totals =	$1,041.62		$1,116.4839	$1,116.48	$1,116.50	$1,116.40