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	$241.47	9.181%	$263.6394	$263.64	$263.65	$263.60
Purchase #2	$95.47	5.144%	$100.381	$100.38	$100.40	$100.40
Purchase #3	$175.51	13.356%	$198.9511	$198.95	$198.95	$199.00
Purchase #4	$102.81	5.333%	$108.2929	$108.29	$108.30	$108.30
Purchase #5	$89.36	9.502%	$97.851	$97.85	$97.85	$97.90
Purchase #6	$97.69	9.160%	$106.6384	$106.64	$106.65	$106.60
Purchase #7	$215.44	9.207%	$235.2756	$235.28	$235.30	$235.30
7 purchase totals =	$1,017.75		$1,111.0294	$1,111.03	$1,111.10	$1,111.10