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	$59.53	3.464%	$61.5921	$61.59	$61.60	$61.60
Purchase #2	$176.80	5.467%	$186.4657	$186.47	$186.45	$186.50
Purchase #3	$131.46	3.206%	$135.6746	$135.67	$135.65	$135.70
Purchase #4	$96.62	3.845%	$100.335	$100.34	$100.35	$100.30
Purchase #5	$170.93	9.351%	$186.9137	$186.91	$186.90	$186.90
Purchase #6	$166.90	13.623%	$189.6368	$189.64	$189.65	$189.60
Purchase #7	$140.25	8.608%	$152.3227	$152.32	$152.30	$152.30
7 purchase totals =	$942.49		$1,012.9406	$1,012.94	$1,012.90	$1,012.90