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	$167.76	10.756%	$185.8043	$185.80	$185.80	$185.80
Purchase #2	$59.65	11.599%	$66.5688	$66.57	$66.55	$66.60
Purchase #3	$97.70	8.139%	$105.6518	$105.65	$105.65	$105.70
Purchase #4	$180.56	8.624%	$196.1315	$196.13	$196.15	$196.10
Purchase #5	$111.31	12.487%	$125.2093	$125.21	$125.20	$125.20
Purchase #6	$79.56	7.565%	$85.5787	$85.58	$85.60	$85.60
Purchase #7	$240.74	8.484%	$261.1644	$261.16	$261.15	$261.20
7 purchase totals =	$937.28		$1,026.1088	$1,026.10	$1,026.10	$1,026.20