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	$207.32	10.185%	$228.4355	$228.44	$228.45	$228.40
Purchase #2	$93.31	5.136%	$98.1024	$98.10	$98.10	$98.10
Purchase #3	$214.32	6.795%	$228.883	$228.88	$228.90	$228.90
Purchase #4	$52.90	4.871%	$55.4768	$55.48	$55.50	$55.50
Purchase #5	$149.50	11.175%	$166.2066	$166.21	$166.20	$166.20
Purchase #6	$76.72	11.669%	$85.6725	$85.67	$85.65	$85.70
Purchase #7	$232.65	4.124%	$242.2445	$242.24	$242.25	$242.20
7 purchase totals =	$1,026.72		$1,105.0213	$1,105.02	$1,105.05	$1,105.00