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	$175.42	11.750%	$196.0319	$196.03	$196.05	$196.00
Purchase #2	$140.32	10.842%	$155.5335	$155.53	$155.55	$155.50
Purchase #3	$100.56	4.475%	$105.0601	$105.06	$105.05	$105.10
Purchase #4	$65.31	12.117%	$73.2236	$73.22	$73.20	$73.20
Purchase #5	$160.41	7.659%	$172.6958	$172.70	$172.70	$172.70
Purchase #6	$235.93	5.761%	$249.5219	$249.52	$249.50	$249.50
Purchase #7	$70.66	13.688%	$80.3319	$80.33	$80.35	$80.30
7 purchase totals =	$948.61		$1,032.3987	$1,032.39	$1,032.40	$1,032.30