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	$188.31	11.394%	$209.766	$209.77	$209.75	$209.80
Purchase #2	$67.33	8.675%	$73.1709	$73.17	$73.15	$73.20
Purchase #3	$115.52	13.654%	$131.2931	$131.29	$131.30	$131.30
Purchase #4	$200.89	4.346%	$209.6207	$209.62	$209.60	$209.60
Purchase #5	$133.80	13.365%	$151.6824	$151.68	$151.70	$151.70
Purchase #6	$161.59	12.306%	$181.4753	$181.48	$181.50	$181.50
Purchase #7	$144.88	11.288%	$161.2341	$161.23	$161.25	$161.20
7 purchase totals =	$1,012.32		$1,118.2425	$1,118.24	$1,118.25	$1,118.30