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	$7.61	4.343%	$7.9405	$7.94	$7.95	$7.90
Purchase #2	$12.73	13.529%	$14.4522	$14.45	$14.45	$14.50
Purchase #3	$172.92	3.663%	$179.2541	$179.25	$179.25	$179.30
Purchase #4	$59.32	8.589%	$64.415	$64.42	$64.40	$64.40
Purchase #5	$117.52	12.118%	$131.7611	$131.76	$131.75	$131.80
Purchase #6	$217.62	4.870%	$228.2181	$228.22	$228.20	$228.20
Purchase #7	$118.64	8.155%	$128.3151	$128.32	$128.30	$128.30
7 purchase totals =	$706.36		$754.3561	$754.36	$754.30	$754.40