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	$130.67	12.516%	$147.0247	$147.02	$147.00	$147.00
Purchase #2	$109.35	12.582%	$123.1084	$123.11	$123.10	$123.10
Purchase #3	$145.60	8.681%	$158.2395	$158.24	$158.25	$158.20
Purchase #4	$45.66	11.559%	$50.9378	$50.94	$50.95	$50.90
Purchase #5	$68.38	5.370%	$72.052	$72.05	$72.05	$72.10
Purchase #6	$187.94	3.681%	$194.8581	$194.86	$194.85	$194.90
Purchase #7	$196.68	11.536%	$219.369	$219.37	$219.35	$219.40
7 purchase totals =	$884.28		$965.5895	$965.59	$965.55	$965.60