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	$118.52	11.564%	$132.2257	$132.23	$132.25	$132.20
Purchase #2	$110.72	5.782%	$117.1218	$117.12	$117.10	$117.10
Purchase #3	$86.30	4.121%	$89.8564	$89.86	$89.85	$89.90
Purchase #4	$37.72	6.501%	$40.1722	$40.17	$40.15	$40.20
Purchase #5	$220.28	3.857%	$228.7762	$228.78	$228.80	$228.80
Purchase #6	$189.96	6.735%	$202.7538	$202.75	$202.75	$202.80
Purchase #7	$233.88	7.112%	$250.5135	$250.51	$250.50	$250.50
7 purchase totals =	$997.38		$1,061.4196	$1,061.42	$1,061.40	$1,061.50