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	$105.64	5.786%	$111.7523	$111.75	$111.75	$111.80
Purchase #2	$201.42	3.609%	$208.6892	$208.69	$208.70	$208.70
Purchase #3	$135.58	7.750%	$146.0875	$146.09	$146.10	$146.10
Purchase #4	$93.72	7.442%	$100.6946	$100.69	$100.70	$100.70
Purchase #5	$130.73	12.806%	$147.4713	$147.47	$147.45	$147.50
Purchase #6	$182.69	4.664%	$191.2107	$191.21	$191.20	$191.20
Purchase #7	$100.84	4.484%	$105.3617	$105.36	$105.35	$105.40
7 purchase totals =	$950.62		$1,011.2673	$1,011.26	$1,011.25	$1,011.40