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	$104.98	4.154%	$109.3409	$109.34	$109.35	$109.30
Purchase #2	$99.31	12.171%	$111.397	$111.40	$111.40	$111.40
Purchase #3	$110.73	5.156%	$116.4392	$116.44	$116.45	$116.40
Purchase #4	$185.49	3.171%	$191.3719	$191.37	$191.35	$191.40
Purchase #5	$166.71	9.150%	$181.964	$181.96	$181.95	$182.00
Purchase #6	$198.89	5.776%	$210.3779	$210.38	$210.40	$210.40
Purchase #7	$174.46	13.187%	$197.466	$197.47	$197.45	$197.50
7 purchase totals =	$1,040.57		$1,118.3569	$1,118.36	$1,118.35	$1,118.40