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	$168.80	7.716%	$181.8246	$181.82	$181.80	$181.80
Purchase #2	$194.88	7.840%	$210.1586	$210.16	$210.15	$210.20
Purchase #3	$54.91	9.258%	$59.9936	$59.99	$60.00	$60.00
Purchase #4	$34.80	8.418%	$37.7295	$37.73	$37.75	$37.70
Purchase #5	$106.91	11.218%	$118.9032	$118.90	$118.90	$118.90
Purchase #6	$165.92	4.199%	$172.887	$172.89	$172.90	$172.90
Purchase #7	$229.37	13.595%	$260.5529	$260.55	$260.55	$260.60
7 purchase totals =	$955.59		$1,042.0494	$1,042.04	$1,042.05	$1,042.10