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	$79.37	8.383%	$86.0236	$86.02	$86.00	$86.00
Purchase #2	$153.57	5.497%	$162.0117	$162.01	$162.00	$162.00
Purchase #3	$29.46	11.511%	$32.8511	$32.85	$32.85	$32.90
Purchase #4	$179.61	10.751%	$198.9199	$198.92	$198.90	$198.90
Purchase #5	$216.49	11.452%	$241.2824	$241.28	$241.30	$241.30
Purchase #6	$159.32	6.529%	$169.722	$169.72	$169.70	$169.70
Purchase #7	$224.71	5.404%	$236.8533	$236.85	$236.85	$236.90
7 purchase totals =	$1,042.53		$1,127.6640	$1,127.65	$1,127.60	$1,127.70