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	$168.32	3.730%	$174.5983	$174.60	$174.60	$174.60
Purchase #2	$69.31	4.643%	$72.5281	$72.53	$72.55	$72.50
Purchase #3	$94.38	8.639%	$102.5335	$102.53	$102.55	$102.50
Purchase #4	$181.38	3.415%	$187.5741	$187.57	$187.55	$187.60
Purchase #5	$56.98	10.277%	$62.8358	$62.84	$62.85	$62.80
Purchase #6	$61.58	4.520%	$64.3634	$64.36	$64.35	$64.40
Purchase #7	$58.80	13.217%	$66.5716	$66.57	$66.55	$66.60
7 purchase totals =	$690.75		$731.0048	$731.00	$731.00	$731.00