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	$179.26	9.403%	$196.1158	$196.12	$196.10	$196.10
Purchase #2	$93.82	4.540%	$98.0794	$98.08	$98.10	$98.10
Purchase #3	$182.58	6.597%	$194.6248	$194.62	$194.60	$194.60
Purchase #4	$147.58	10.339%	$162.8383	$162.84	$162.85	$162.80
Purchase #5	$179.38	10.417%	$198.066	$198.07	$198.05	$198.10
Purchase #6	$46.86	11.212%	$52.1139	$52.11	$52.10	$52.10
Purchase #7	$244.25	8.705%	$265.512	$265.51	$265.50	$265.50
7 purchase totals =	$1,073.73		$1,167.3502	$1,167.35	$1,167.30	$1,167.30