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	$161.32	3.711%	$167.3066	$167.31	$167.30	$167.30
Purchase #2	$68.47	3.805%	$71.0753	$71.08	$71.10	$71.10
Purchase #3	$44.77	4.768%	$46.9046	$46.90	$46.90	$46.90
Purchase #4	$174.55	4.473%	$182.3576	$182.36	$182.35	$182.40
Purchase #5	$212.33	9.719%	$232.9664	$232.97	$232.95	$233.00
Purchase #6	$120.86	5.550%	$127.5677	$127.57	$127.55	$127.60
Purchase #7	$38.37	11.420%	$42.7519	$42.75	$42.75	$42.80
7 purchase totals =	$820.67		$870.9301	$870.94	$870.90	$871.10