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	$116.63	7.387%	$125.2455	$125.25	$125.25	$125.20
Purchase #2	$15.72	9.634%	$17.2345	$17.23	$17.25	$17.20
Purchase #3	$225.79	11.656%	$252.1081	$252.11	$252.10	$252.10
Purchase #4	$48.69	12.328%	$54.6925	$54.69	$54.70	$54.70
Purchase #5	$78.86	13.651%	$89.6252	$89.63	$89.65	$89.60
Purchase #6	$176.64	5.762%	$186.818	$186.82	$186.80	$186.80
Purchase #7	$192.39	12.543%	$216.5215	$216.52	$216.50	$216.50
7 purchase totals =	$854.72		$942.2453	$942.25	$942.25	$942.10