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	$197.29	11.144%	$219.276	$219.28	$219.30	$219.30
Purchase #2	$83.85	5.657%	$88.5934	$88.59	$88.60	$88.60
Purchase #3	$247.93	10.354%	$273.6007	$273.60	$273.60	$273.60
Purchase #4	$224.34	7.658%	$241.52	$241.52	$241.50	$241.50
Purchase #5	$61.82	9.174%	$67.4914	$67.49	$67.50	$67.50
Purchase #6	$64.57	11.341%	$71.8929	$71.89	$71.90	$71.90
Purchase #7	$76.32	10.432%	$84.2817	$84.28	$84.30	$84.30
7 purchase totals =	$956.12		$1,046.6561	$1,046.65	$1,046.70	$1,046.70