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	$186.25	5.623%	$196.7228	$196.72	$196.70	$196.70
Purchase #2	$208.44	10.333%	$229.9781	$229.98	$230.00	$230.00
Purchase #3	$31.29	12.131%	$35.0858	$35.09	$35.10	$35.10
Purchase #4	$187.48	12.569%	$211.0444	$211.04	$211.05	$211.00
Purchase #5	$185.27	10.827%	$205.3292	$205.33	$205.35	$205.30
Purchase #6	$199.43	11.864%	$223.0904	$223.09	$223.10	$223.10
Purchase #7	$44.60	13.687%	$50.7044	$50.70	$50.70	$50.70
7 purchase totals =	$1,042.76		$1,151.9551	$1,151.95	$1,152.00	$1,151.90