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	$213.61	5.135%	$224.5789	$224.58	$224.60	$224.60
Purchase #2	$203.94	4.702%	$213.5293	$213.53	$213.55	$213.50
Purchase #3	$147.59	3.181%	$152.2848	$152.28	$152.30	$152.30
Purchase #4	$102.84	6.865%	$109.9	$109.90	$109.90	$109.90
Purchase #5	$144.85	9.196%	$158.1704	$158.17	$158.15	$158.20
Purchase #6	$127.33	7.177%	$136.4685	$136.47	$136.45	$136.50
Purchase #7	$150.99	12.187%	$169.3912	$169.39	$169.40	$169.40
7 purchase totals =	$1,091.15		$1,164.3231	$1,164.32	$1,164.35	$1,164.40