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	$168.87	3.490%	$174.7636	$174.76	$174.75	$174.80
Purchase #2	$96.84	5.427%	$102.0955	$102.10	$102.10	$102.10
Purchase #3	$9.83	6.190%	$10.4385	$10.44	$10.45	$10.40
Purchase #4	$16.33	12.598%	$18.3873	$18.39	$18.40	$18.40
Purchase #5	$83.32	3.371%	$86.1287	$86.13	$86.15	$86.10
Purchase #6	$98.89	6.123%	$104.945	$104.95	$104.95	$104.90
Purchase #7	$94.45	7.352%	$101.394	$101.39	$101.40	$101.40
7 purchase totals =	$568.53		$598.1526	$598.16	$598.20	$598.10