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	$182.29	12.401%	$204.8958	$204.90	$204.90	$204.90
Purchase #2	$214.34	13.806%	$243.9318	$243.93	$243.95	$243.90
Purchase #3	$55.91	7.166%	$59.9165	$59.92	$59.90	$59.90
Purchase #4	$40.73	12.352%	$45.761	$45.76	$45.75	$45.80
Purchase #5	$18.79	3.166%	$19.3849	$19.38	$19.40	$19.40
Purchase #6	$248.86	3.847%	$258.4336	$258.43	$258.45	$258.40
Purchase #7	$163.52	11.579%	$182.454	$182.45	$182.45	$182.50
7 purchase totals =	$924.44		$1,014.7776	$1,014.77	$1,014.80	$1,014.80