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	$190.44	3.419%	$196.9511	$196.95	$196.95	$197.00
Purchase #2	$19.28	7.813%	$20.7863	$20.79	$20.80	$20.80
Purchase #3	$53.72	4.235%	$55.995	$56.00	$56.00	$56.00
Purchase #4	$5.78	9.333%	$6.3194	$6.32	$6.30	$6.30
Purchase #5	$153.47	11.619%	$171.3017	$171.30	$171.30	$171.30
Purchase #6	$22.31	11.294%	$24.8297	$24.83	$24.85	$24.80
Purchase #7	$90.47	10.368%	$99.8499	$99.85	$99.85	$99.80
7 purchase totals =	$535.47		$576.0331	$576.04	$576.05	$576.00