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	$115.60	8.532%	$125.463	$125.46	$125.45	$125.50
Purchase #2	$43.92	11.865%	$49.1311	$49.13	$49.15	$49.10
Purchase #3	$247.96	6.179%	$263.2814	$263.28	$263.30	$263.30
Purchase #4	$79.47	13.596%	$90.2747	$90.27	$90.25	$90.30
Purchase #5	$150.27	12.653%	$169.2837	$169.28	$169.30	$169.30
Purchase #6	$158.38	6.379%	$168.4831	$168.48	$168.50	$168.50
Purchase #7	$141.49	13.708%	$160.8854	$160.89	$160.90	$160.90
7 purchase totals =	$937.09		$1,026.8024	$1,026.79	$1,026.85	$1,026.90