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	$211.69	7.729%	$228.0515	$228.05	$228.05	$228.10
Purchase #2	$71.58	13.311%	$81.108	$81.11	$81.10	$81.10
Purchase #3	$58.95	4.283%	$61.4748	$61.47	$61.45	$61.50
Purchase #4	$196.40	10.268%	$216.5664	$216.57	$216.55	$216.60
Purchase #5	$55.50	10.745%	$61.4635	$61.46	$61.45	$61.50
Purchase #6	$216.27	11.716%	$241.6082	$241.61	$241.60	$241.60
Purchase #7	$233.57	3.625%	$242.0369	$242.04	$242.05	$242.00
7 purchase totals =	$1,043.96		$1,132.3093	$1,132.31	$1,132.25	$1,132.40