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	$213.49	11.238%	$237.482	$237.48	$237.50	$237.50
Purchase #2	$162.70	7.216%	$174.4404	$174.44	$174.45	$174.40
Purchase #3	$181.95	3.487%	$188.2946	$188.29	$188.30	$188.30
Purchase #4	$102.52	9.599%	$112.3609	$112.36	$112.35	$112.40
Purchase #5	$175.33	5.169%	$184.3928	$184.39	$184.40	$184.40
Purchase #6	$152.85	6.358%	$162.5682	$162.57	$162.55	$162.60
Purchase #7	$146.59	3.229%	$151.3234	$151.32	$151.30	$151.30
7 purchase totals =	$1,135.43		$1,210.8623	$1,210.85	$1,210.85	$1,210.90