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	$91.82	4.408%	$95.8674	$95.87	$95.85	$95.90
Purchase #2	$82.89	3.619%	$85.8898	$85.89	$85.90	$85.90
Purchase #3	$20.35	3.312%	$21.024	$21.02	$21.00	$21.00
Purchase #4	$39.41	9.711%	$43.2371	$43.24	$43.25	$43.20
Purchase #5	$92.66	5.707%	$97.9481	$97.95	$97.95	$97.90
Purchase #6	$127.83	4.203%	$133.2027	$133.20	$133.20	$133.20
Purchase #7	$65.34	10.411%	$72.1425	$72.14	$72.15	$72.10
7 purchase totals =	$520.30		$549.3116	$549.31	$549.30	$549.20