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	$195.42	12.143%	$219.1499	$219.15	$219.15	$219.10
Purchase #2	$29.33	6.737%	$31.306	$31.31	$31.30	$31.30
Purchase #3	$235.52	11.867%	$263.4692	$263.47	$263.45	$263.50
Purchase #4	$151.67	13.385%	$171.971	$171.97	$171.95	$172.00
Purchase #5	$96.82	12.666%	$109.0832	$109.08	$109.10	$109.10
Purchase #6	$116.59	12.564%	$131.2384	$131.24	$131.25	$131.20
Purchase #7	$118.71	10.135%	$130.7413	$130.74	$130.75	$130.70
7 purchase totals =	$944.06		$1,056.9590	$1,056.96	$1,056.95	$1,056.90