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	$148.76	9.453%	$162.8223	$162.82	$162.80	$162.80
Purchase #2	$146.25	11.151%	$162.5583	$162.56	$162.55	$162.60
Purchase #3	$32.31	13.270%	$36.5975	$36.60	$36.60	$36.60
Purchase #4	$247.98	4.564%	$259.2978	$259.30	$259.30	$259.30
Purchase #5	$98.73	6.131%	$104.7831	$104.78	$104.80	$104.80
Purchase #6	$59.70	3.703%	$61.9107	$61.91	$61.90	$61.90
Purchase #7	$26.85	5.780%	$28.4019	$28.40	$28.40	$28.40
7 purchase totals =	$760.58		$816.3716	$816.37	$816.35	$816.40