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	$191.58	13.489%	$217.4222	$217.42	$217.40	$217.40
Purchase #2	$47.91	13.189%	$54.2288	$54.23	$54.25	$54.20
Purchase #3	$52.44	7.664%	$56.459	$56.46	$56.45	$56.50
Purchase #4	$52.30	9.576%	$57.3082	$57.31	$57.30	$57.30
Purchase #5	$225.38	7.729%	$242.7996	$242.80	$242.80	$242.80
Purchase #6	$212.70	4.646%	$222.582	$222.58	$222.60	$222.60
Purchase #7	$168.38	3.385%	$174.0797	$174.08	$174.10	$174.10
7 purchase totals =	$950.69		$1,024.8795	$1,024.88	$1,024.90	$1,024.90