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	$95.50	4.557%	$99.8519	$99.85	$99.85	$99.90
Purchase #2	$88.31	9.709%	$96.884	$96.88	$96.90	$96.90
Purchase #3	$31.94	6.753%	$34.0969	$34.10	$34.10	$34.10
Purchase #4	$10.46	9.124%	$11.4144	$11.41	$11.40	$11.40
Purchase #5	$69.79	8.198%	$75.5114	$75.51	$75.50	$75.50
Purchase #6	$197.82	3.716%	$205.171	$205.17	$205.15	$205.20
Purchase #7	$41.52	9.220%	$45.3481	$45.35	$45.35	$45.30
7 purchase totals =	$535.34		$568.2777	$568.27	$568.25	$568.30