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	$205.31	8.170%	$222.0838	$222.08	$222.10	$222.10
Purchase #2	$177.48	12.858%	$200.3004	$200.30	$200.30	$200.30
Purchase #3	$5.29	6.459%	$5.6317	$5.63	$5.65	$5.60
Purchase #4	$109.34	3.640%	$113.32	$113.32	$113.30	$113.30
Purchase #5	$173.45	5.252%	$182.5596	$182.56	$182.55	$182.60
Purchase #6	$119.68	9.111%	$130.584	$130.58	$130.60	$130.60
Purchase #7	$151.90	5.601%	$160.4079	$160.41	$160.40	$160.40
7 purchase totals =	$942.45		$1,014.8874	$1,014.88	$1,014.90	$1,014.90