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	$191.54	8.139%	$207.1294	$207.13	$207.15	$207.10
Purchase #2	$82.46	7.394%	$88.5571	$88.56	$88.55	$88.60
Purchase #3	$187.48	5.724%	$198.2114	$198.21	$198.20	$198.20
Purchase #4	$45.38	10.670%	$50.222	$50.22	$50.20	$50.20
Purchase #5	$74.35	5.186%	$78.2058	$78.21	$78.20	$78.20
Purchase #6	$147.51	3.367%	$152.4767	$152.48	$152.50	$152.50
Purchase #7	$244.89	13.671%	$278.3689	$278.37	$278.35	$278.40
7 purchase totals =	$973.61		$1,053.1713	$1,053.18	$1,053.15	$1,053.20