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	$162.27	12.123%	$181.942	$181.94	$181.95	$181.90
Purchase #2	$171.45	12.261%	$192.4715	$192.47	$192.45	$192.50
Purchase #3	$129.61	6.709%	$138.3055	$138.31	$138.30	$138.30
Purchase #4	$79.96	8.269%	$86.5719	$86.57	$86.55	$86.60
Purchase #5	$162.54	3.624%	$168.4304	$168.43	$168.45	$168.40
Purchase #6	$160.36	4.120%	$166.9668	$166.97	$166.95	$167.00
Purchase #7	$104.56	6.778%	$111.6471	$111.65	$111.65	$111.60
7 purchase totals =	$970.75		$1,046.3352	$1,046.34	$1,046.30	$1,046.30