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	$119.84	6.299%	$127.3887	$127.39	$127.40	$127.40
Purchase #2	$171.50	6.196%	$182.1261	$182.13	$182.15	$182.10
Purchase #3	$153.51	3.783%	$159.3173	$159.32	$159.30	$159.30
Purchase #4	$25.26	12.747%	$28.4799	$28.48	$28.50	$28.50
Purchase #5	$216.52	5.679%	$228.8162	$228.82	$228.80	$228.80
Purchase #6	$136.75	11.238%	$152.118	$152.12	$152.10	$152.10
Purchase #7	$140.84	3.187%	$145.3286	$145.33	$145.35	$145.30
7 purchase totals =	$964.22		$1,023.5748	$1,023.59	$1,023.60	$1,023.50