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	$92.65	5.728%	$97.957	$97.96	$97.95	$98.00
Purchase #2	$172.26	8.626%	$187.1191	$187.12	$187.10	$187.10
Purchase #3	$159.74	4.659%	$167.1823	$167.18	$167.20	$167.20
Purchase #4	$145.91	4.270%	$152.1404	$152.14	$152.15	$152.10
Purchase #5	$140.37	9.317%	$153.4483	$153.45	$153.45	$153.40
Purchase #6	$175.69	5.648%	$185.613	$185.61	$185.60	$185.60
Purchase #7	$104.43	12.697%	$117.6895	$117.69	$117.70	$117.70
7 purchase totals =	$991.05		$1,061.1496	$1,061.15	$1,061.15	$1,061.10