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	$175.32	11.261%	$195.0628	$195.06	$195.05	$195.10
Purchase #2	$168.70	3.478%	$174.5674	$174.57	$174.55	$174.60
Purchase #3	$211.70	12.494%	$238.1498	$238.15	$238.15	$238.10
Purchase #4	$84.57	12.836%	$95.4254	$95.43	$95.45	$95.40
Purchase #5	$141.91	8.455%	$153.9085	$153.91	$153.90	$153.90
Purchase #6	$154.45	7.624%	$166.2253	$166.23	$166.25	$166.20
Purchase #7	$118.83	6.808%	$126.9199	$126.92	$126.90	$126.90
7 purchase totals =	$1,055.48		$1,150.2591	$1,150.27	$1,150.25	$1,150.20