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	$148.29	10.785%	$164.2831	$164.28	$164.30	$164.30
Purchase #2	$162.41	4.255%	$169.3205	$169.32	$169.30	$169.30
Purchase #3	$201.54	7.490%	$216.6353	$216.64	$216.65	$216.60
Purchase #4	$93.45	5.506%	$98.5954	$98.60	$98.60	$98.60
Purchase #5	$117.41	6.633%	$125.1978	$125.20	$125.20	$125.20
Purchase #6	$173.80	13.103%	$196.573	$196.57	$196.55	$196.60
Purchase #7	$113.52	4.482%	$118.608	$118.61	$118.60	$118.60
7 purchase totals =	$1,010.42		$1,089.2131	$1,089.22	$1,089.20	$1,089.20