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	$147.64	10.161%	$162.6417	$162.64	$162.65	$162.60
Purchase #2	$43.63	13.518%	$49.5279	$49.53	$49.55	$49.50
Purchase #3	$22.89	12.564%	$25.7659	$25.77	$25.75	$25.80
Purchase #4	$248.59	6.131%	$263.8311	$263.83	$263.85	$263.80
Purchase #5	$167.61	11.326%	$186.5935	$186.59	$186.60	$186.60
Purchase #6	$207.82	9.829%	$228.2466	$228.25	$228.25	$228.20
Purchase #7	$39.76	10.399%	$43.8946	$43.89	$43.90	$43.90
7 purchase totals =	$877.94		$960.5013	$960.50	$960.55	$960.40