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	$167.58	11.179%	$186.3138	$186.31	$186.30	$186.30
Purchase #2	$188.78	3.562%	$195.5043	$195.50	$195.50	$195.50
Purchase #3	$40.89	5.310%	$43.0613	$43.06	$43.05	$43.10
Purchase #4	$208.53	8.655%	$226.5783	$226.58	$226.60	$226.60
Purchase #5	$146.94	10.306%	$162.0836	$162.08	$162.10	$162.10
Purchase #6	$86.92	13.479%	$98.6359	$98.64	$98.65	$98.60
Purchase #7	$162.38	7.191%	$174.0567	$174.06	$174.05	$174.10
7 purchase totals =	$1,002.02		$1,086.2339	$1,086.23	$1,086.25	$1,086.30