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	$173.95	11.862%	$194.5839	$194.58	$194.60	$194.60
Purchase #2	$228.96	7.607%	$246.377	$246.38	$246.40	$246.40
Purchase #3	$250.39	5.172%	$263.3402	$263.34	$263.35	$263.30
Purchase #4	$34.44	7.806%	$37.1284	$37.13	$37.15	$37.10
Purchase #5	$94.43	12.110%	$105.8655	$105.87	$105.85	$105.90
Purchase #6	$121.54	3.166%	$125.388	$125.39	$125.40	$125.40
Purchase #7	$164.51	12.825%	$185.6084	$185.61	$185.60	$185.60
7 purchase totals =	$1,068.22		$1,158.2914	$1,158.30	$1,158.35	$1,158.30