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	$214.40	11.113%	$238.2263	$238.23	$238.25	$238.20
Purchase #2	$154.25	9.494%	$168.8945	$168.89	$168.90	$168.90
Purchase #3	$27.42	3.537%	$28.3898	$28.39	$28.40	$28.40
Purchase #4	$162.31	4.296%	$169.2828	$169.28	$169.30	$169.30
Purchase #5	$225.77	12.463%	$253.9077	$253.91	$253.90	$253.90
Purchase #6	$79.79	7.790%	$86.0056	$86.01	$86.00	$86.00
Purchase #7	$45.29	10.442%	$50.0192	$50.02	$50.00	$50.00
7 purchase totals =	$909.23		$994.7259	$994.73	$994.75	$994.70