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	$185.77	6.288%	$197.4512	$197.45	$197.45	$197.50
Purchase #2	$6.74	12.234%	$7.5646	$7.56	$7.55	$7.60
Purchase #3	$177.97	6.323%	$189.223	$189.22	$189.20	$189.20
Purchase #4	$164.73	3.737%	$170.886	$170.89	$170.90	$170.90
Purchase #5	$132.35	6.638%	$141.1354	$141.14	$141.15	$141.10
Purchase #6	$49.45	13.786%	$56.2672	$56.27	$56.25	$56.30
Purchase #7	$233.31	8.774%	$253.7806	$253.78	$253.80	$253.80
7 purchase totals =	$950.32		$1,016.3080	$1,016.31	$1,016.30	$1,016.40