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	$200.40	5.728%	$211.8789	$211.88	$211.90	$211.90
Purchase #2	$167.68	13.763%	$190.7578	$190.76	$190.75	$190.80
Purchase #3	$178.56	12.316%	$200.5514	$200.55	$200.55	$200.60
Purchase #4	$62.52	11.842%	$69.9236	$69.92	$69.90	$69.90
Purchase #5	$130.92	6.418%	$139.3224	$139.32	$139.30	$139.30
Purchase #6	$8.88	7.804%	$9.573	$9.57	$9.55	$9.60
Purchase #7	$212.43	9.800%	$233.2481	$233.25	$233.25	$233.20
7 purchase totals =	$961.39		$1,055.2552	$1,055.25	$1,055.20	$1,055.30