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	$197.71	10.263%	$218.001	$218.00	$218.00	$218.00
Purchase #2	$50.25	8.481%	$54.5117	$54.51	$54.50	$54.50
Purchase #3	$168.48	8.337%	$182.5262	$182.53	$182.55	$182.50
Purchase #4	$90.28	5.188%	$94.9637	$94.96	$94.95	$95.00
Purchase #5	$174.95	11.172%	$194.4954	$194.50	$194.50	$194.50
Purchase #6	$51.29	3.569%	$53.1205	$53.12	$53.10	$53.10
Purchase #7	$179.89	3.254%	$185.7436	$185.74	$185.75	$185.70
7 purchase totals =	$912.85		$983.3621	$983.36	$983.35	$983.30