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	$164.96	11.540%	$183.9964	$184.00	$184.00	$184.00
Purchase #2	$50.75	3.566%	$52.5597	$52.56	$52.55	$52.60
Purchase #3	$140.50	4.152%	$146.3336	$146.33	$146.35	$146.30
Purchase #4	$168.59	6.585%	$179.6917	$179.69	$179.70	$179.70
Purchase #5	$213.50	6.472%	$227.3177	$227.32	$227.30	$227.30
Purchase #6	$71.49	12.475%	$80.4084	$80.41	$80.40	$80.40
Purchase #7	$165.95	10.528%	$183.4212	$183.42	$183.40	$183.40
7 purchase totals =	$975.74		$1,053.7287	$1,053.73	$1,053.70	$1,053.70